The Plant Body

Longest Pines Recorded

On November 1, 2002, John Quigley climbed into the branches of a 70-foot-tall oak tree estimated to be 150 to 400 years old. He stayed perched there until he was removed, 71 days later, to allow a housing developer to cut down the tree. That was a short stay, however, compared with Julia Butterfly Hill's sojourn in a 600-year-old redwood. In the year 2000, Hill created a perch 180 feet above ground and didn't come down to Earth until just over 2 years later, when the Pacific Lumber Company...

The Genetics of Behavior

Hierarchy Control Maritime

To say that behavior is inherited does not mean that specific genes code for specific behaviors. Genes code for proteins, and there are many complex steps between the expression of a gene as a protein product and the expression of a behavior. In no case are all the steps between a gene and its influence on a behavior known. Nevertheless, it is clear that behavior has genetic determinants. In this section we will look at three approaches to investigating how genes affect behavior hybridization,...

Some cancers are caused by viruses

Peyton Rous's discovery in 1910 that a sarcoma in chickens is caused by a virus that is transmitted from one bird to another spawned an intensive search for cancer-causing viruses in humans. At least five types of human cancer are probably caused by viruses (Table 17.1). Hepatitis B, a liver disease that affects people all over the world, is caused by the hepatitis B virus, which contaminates blood or is carried from mother to child during birth. The viral infection can be long-lasting and may...

Ggacacctc Cctgtggag

Membrane Cancer Cells

AS AS AA AS Genotypes of family members deduced from allele-specific hybridization AS AS AA AS Genotypes of family members deduced from allele-specific hybridization 17.13 A Cancer Cell with Its Normal Neighbors This small-cell lung cancer cell yellow green is quite different from the surrounding lung epithelial cells from which it came. This particular form of cancer is very lethal, with a 5-year survival rate of less than 10 percent. Most cases are caused by smoking. 17.13 A Cancer Cell with...

Info

3.22 b-Carotene is the Source of Vitamin A The carotenoid P-carotene is symmetrical around its central double bond when split, P-carotene becomes two vitamin A molecules.The simplified structural formula used here is standard chemical shorthand for large organic molecules with many carbon atoms. Structural formulas are simplified by omitting the C indicating a carbon atom at the intersections of the lines representing covalent bonds. Hydrogen atoms H to fill all the available bonding sites on...

Sources of energy can be stored in the body

Steps Starvation

Although the cells of the body use energy continuously, most animals do not eat continuously. Therefore, animals must store fuel molecules that can be released as needed between meals. Carbohydrates are stored in liver and muscle cells as glyco-gen, but the total glycogen store represents only about a day's basal energy requirements 1,500-2,000 Cal . Fat is the most important form of stored energy in the bodies of animals. Not only does fat have more energy per gram than glycogen, but it can be...

Regulation of hormone receptors controls the sensitivity of cells to hormones

We saw above that the release of hormones can be under feedback control, usually negative feedback control. Similarly, the abundance of receptors for a hormone can be under feedback control. In some cases, continuous high levels of a hormone can decrease the number of its receptors, a process known as downregulation. Upregulation of receptors, or an increase in their abundance, is a positive feedback mechanism, and is less common. An example of downregulation is type II diabetes mellitus, which...

Fertilizers and lime are used in agriculture

Agricultural soils often require fertilizers because irrigation and rainwater leach mineral nutrients from the soil and because the harvesting of crops removes the nutrients that the plants took up from the soil during their growth. Crop yields decrease if any essential element is depleted. Mineral nutrients may be replaced by organic fertilizers, such as rotted manure, or by inorganic fertilizers of various types. organic and inorganic fertilizers. The three elements most commonly added to...

Cancer cells differ from their normal counterparts

Cancer cells differ from the normal cells from which they originate in two major ways. CANCER CELLS LOSE CONTROL OVER CELL DIVISION. Most cells in the body divide only if they are exposed to extracellular influences, such as growth factors or hormones. Cancer cells do not respond to these controls, and instead divide more or less continuously, ultimately forming tumors large masses of cells . By the time a physician can feel a tumor or see one on an X ray or CAT scan, it already contains...

Decreasing heat loss is important for life in the cold

The coldest habitats on Earth are in the Arctic, the Antarctic, and at the peaks of high mountains. Many birds and mammals, but almost no reptiles or amphibians, live in these places. What adaptations besides endothermy characterize species that live in the cold The most important adaptations of endotherms to cold environments are those that reduce heat loss to the environment. Since most heat is lost from the body surface, many cold-climate species have a smaller surface area than their...

Lipoproteins The good the bad and the ugly

In the intestine, bile solves the problem of processing hy-drophobic fats in an aqueous medium. The transport of fats in the circulatory system presents the same problem, and lipopro-teins are the solution. A lipoprotein is a particle made up of a core of fat and cholesterol and a covering of protein that makes it water-soluble. The largest lipoprotein particles in the bloodstream are the chylomicrons produced by the mucosal cells of the intestine see Figure 50.15 . As the chylomicrons...

T Cells The Cellular Immune Response

Plasma Membrane

Thus far we have been concerned primarily with the humoral immune response, whose effector molecules are the antibodies secreted by plasma cells that develop from activated B cells. T cells, as we have seen, are involved in the humoral immune response, but they are also the effectors of the cellular immune response, which is directed against any factor, such as a virus or mutation, that changes a normal cell into an abnormal cell. In this section, we will describe two types of effector T cells...

Interpretation

Movement Cortex Human

This model would explain the results of cell-to-cell connections. Relay cells Simple cells Complex cells Retinal ganglion cells in thalamus in cortex in cortex Conclusion Cells in the retina, thalamus, and cortex are connected in such a way as to respond to specific patterns of light. Relay cells Simple cells Complex cells Retinal ganglion cells in thalamus in cortex in cortex Conclusion Cells in the retina, thalamus, and cortex are connected in such a way as to respond to specific patterns of...

Most species produce more than one nitrogenous waste

Humans are ureotelic, yet we also excrete uric acid and ammonia. The uric acid in human urine comes largely from the metabolism of nucleic acids and caffeine. In the condition known as gout, uric acid levels in the tissue fluid increase, and uric acid precipitates out of solution in the joints and elsewhere, causing swelling and pain. The excretion of ammonia is an important mechanism for regulating the pH of the tissue fluid. In some species, different developmental stages live in different...

Other Organelles

Typical Plant Cell

Eukaryotic cells have several other organelles that are surrounded by a single membrane. Peroxisomes house specialized chemical reactions Peroxisomes are organelles that collect the toxic peroxides such as hydrogen peroxide, H2O2 that are the unavoidable by-products of chemical reactions. These peroxides can be safely broken down inside the peroxisomes without mixing with other parts of the cell. Peroxisomes are small organelles, about 0.2 to 1.7 m in diameter. They have a single membrane and a...

Uptake and Movement of Water and Solutes

Plant Water And Solute Uptake

Terrestrial plants must obtain both water and mineral nutrients from the soil, usually by way of their roots. The roots, in turn, obtain carbohydrates and other important materials from the leaves Figure 36.1 . We learned in Chapter 8 that water is one of the ingredients required for carbohydrate production by photosynthesis in the leaves. Water is also essential for transporting solutes both upward and downward, for cooling the plant, and for developing the internal pressure that supports the...

Photosynthesis Energy from the

Producers Plants

Powered by sunlight, green plants convert CO2 and water into carbohydrates by a process called photosynthesis. The emergence of this metabolic pathway was a key event in the evolution of life. Photosynthesizing organisms, called autotrophs self-feeders , use solar energy to make their own food from simple chemicals in the environment. In this way, they provide an entry point to the biosphere for chemical energy. Heterotrophs other-feeders cannot photosynthesize, and they depend on autotrophs or...

The adrenal gland is two glands in one

Amine Hormone Adrenal Medulla

An adrenal gland sits above each kidney, just below the middle of your back. Functionally and anatomically, each adrenal gland consists of a gland within a gland Figure 42.10 . The core, called the adrenal medulla, produces the hormone epinephrine also known as adrenaline and, to a lesser degree, norepinephrine or noradrenaline , which also acts as a neurotransmitter in the nervous system . Surrounding the medulla is the adrenal cortex, which produces other hormones. The medulla develops from...

Basal metabolic rates of endotherms are related to body size

Obviously, the total basal metabolic rate of an elephant is greater than that of a mouse. After all, the elephant is more than 100,000 times more massive than the mouse. However, the metabolic rate of the elephant is only about 7,000 times greater than that of the mouse. That means that the metabolism of a gram of mouse tissue is much greater than the metabolism of a gram of elephant tissue more than 20 times greater Figure 41.13 . Across all of the endotherms, basal metabolic rate per gram of...

Skeletal Systems

Knee Joint Almost Bone Bone

To create significant movement, they must have something to pull on. In some cases, muscles pull on each other consider the trunk of the elephant or the arms of an octopus. In most cases, however, skeletal systems provide rigid supports against which muscles can pull, creating directed movements. In this section, we'll examine the three types of skeletal systems found in animals hydrostatic skeletons, exoskeletons, and endoskeletons. A hydrostatic skeleton...

Myriapods have many legs

Centipedes, millipedes, and the two other groups of animals comprise the phylum Myriapoda. Centipedes and millipedes have a well-formed head and a long, flexible, segmented trunk that bears many pairs of legs Figure 33.15 . Centipedes, which have one pair of legs per segment, prey on insects and other small animals. Millipedes, which have two pairs of legs per segment, scavenge and eat plants. More than 3,000 species of centipedes and 10,000 species of millipedes have been described many more...

Chylomicrons Are Like The Tiny Micelles Of Dietary Fat In The Lumen Of The Small Intestine In That Both

Most of the metabolic energy that a bird requires for a longdistance migratory flight is stored as 2. Which statement about essential amino acids is true a. They are not found in vegetarian diets. b. They are stored by the body for the times when they are needed. c. Without them, one is undernourished. d. All animals require the same ones. e. Humans can acquire all of theirs by eating milk, eggs, and meat. 3. Which statement about vitamins is true a. They are essential inorganic nutrients....

Why Are Dikaryons Described As N N Instead Of 2n

You are shown an object that looks superficially like a pale green mushroom. Describe at least three criteria including anatomical and chemical traits that would enable you to tell whether the object is a piece of a plant or a piece of a fungus. 2. Differentiate among the members of the following pairs of related terms 3. For each type of organism listed below, give a single characteristic that may be used to differentiate it from the other, related organism s in parentheses. b....

Sickle Cell Anemia Mutation

Missense Mutation Sickle Cell Anemia

J Cleaving the polypeptide allows the fragments to fold into different shapes. Adding sugars is important for targeting and recognition. Added phosphate groups alter the shape of the protein. most polypeptides are modified after translation, and these modifications are essential to the final functioning of the protein Figure 12.16 . Proteolysis is the cutting of a polypeptide chain. Cleavage of the signal sequence from the growing polypeptide chain in the ER is an example of proteolysis the...

Experiment

Atp Synthesis

Question What is the role of ATP synthase in ATP synthesis A proton pump extracted from bacteria is added to an artificial lipid vesicle. Question What is the role of ATP synthase in ATP synthesis A proton pump extracted from bacteria is added to an artificial lipid vesicle. Conclusion ATP synthase, acting as an H channel, is necessary for ATP synthesis. Conclusion ATP synthase, acting as an H channel, is necessary for ATP synthesis. When cells capable of fermentation become anaerobic, the rate...

Four features characterize the immune system

Antigen And Antibody Symbols

The characteristic features of the immune system are specificity, the ability to respond to an enormous diversity of foreign molecules and organisms, the ability to distinguish self from nonself, and immunological memory. I A fragment of a bacterium binds to the receptor CD14. I A fragment of a bacterium binds to the receptor CD14. The transcription factor, NF-kB is phosphorylated. The transcription factor, NF-kB is phosphorylated. 18.5 Cell Signaling and Defense Binding of a molecule from a...

Carnivorous and Heterotrophic Plants

Heterotrophic Plants

Some plants that are found primarily in nitrogen-deficient soils augment their nitrogen and phosphorus supply by capturing and digesting flies and other insects. There are about 450 of these carnivorous species, the best-known of which are Venus flytraps genus Dionaea Figure 37.9a , sundews genus Drosera Figure 37.9b , and pitcher plants genus Sarracenia . Carnivorous plants are normally found in boggy regions where the soil is acidic. Most decomposing organisms require a less acidic pH to...

Disorders of the Immune System

Sometimes the immune system fails us in one way or another. It may overreact, as in an allergic reaction it may attack self antigens, as in an autoimmune disease or it may function weakly or not at all, as in an immune deficiency disease. After a look at allergies and autoimmune diseases, we will examine the acquired immune deficiency that characterizes AIDS. hypersensitivity. A common type of condition arises when the human immune system overreacts to is hypersensitive to a dose of antigen....

General Biology of the Protists

Amoeba Membrane Surface Area

Some live in marine environments, others in fresh water, and still others in the body fluids of other organisms. The slime molds inhabit damp soil and the moist, decaying bark of rotting trees. Many other protists also live in soil water, some of them contributing to the global nitrogen cycle by preying on soil bacteria and recycling their nitrogen compounds into nitrates. Most protists are unicellular, but some are multicellular, and a few are very large. Protists...

Plasma Membrane

Animal Critical Temperatures

Lower Upper critical critical temperature temperature Below the lower critical temperature, the animal produces metabolic heat to compensate for increased heat loss to the environment. Above the upper critical temperature, the animal must expend energy to lose heat by panting or sweating, which makes its metabolic rate increase. Below the lower critical temperature, the animal produces metabolic heat to compensate for increased heat loss to the environment. Above the upper critical temperature,...

Thyroxine controls cell metabolism

The thyroid gland wraps around the front of the windpipe trachea and expands into a lobe on either side see Figure 42.2 . The thyroid gland produces the hormones thyroxine and calcitonin. It contains many round structures, called follicles, that produce, store, and release thyroxine. Cells in the spaces between the follicles produce calcitonin. Thyroxine is synthesized from two molecules of tyrosine, which then have four atoms of iodine chemically bonded to them. Thus, the thyroxine molecule is...

The Role of Differential Gene Expression in Establishing Body Segmentation

Drosophila Maternal Gene Nanos Bicoid

Insects such as the fruit fly Drosophila melanogaster develop a highly modular body composed of different types of segments. Complex interactions of different sets of genes underlie the pattern formation of segmented bodies. Unlike the body segments of segmented worms such as earthworms, which are all essentially alike, the segments of the Drosophila body are clearly different from one another. The adult fly has an anterior head composed of several fused segments , three different thoracic...

Hormones can be divided into three chemical groups

There is enormous diversity in the chemical structure of hormones, but most of them can be divided into three groups Peptides or proteins e.g., insulin Steroid hormones derivatives of the steroid cholesterol e.g., testosterone Amines derivatives of the amino acid tyrosine e.g., thyroxine Most hormones are peptides or proteins. They are water-soluble and therefore easily transported in the blood, but they cannot easily pass through lipid-rich cell membranes. Therefore, peptide and protein...

The pressure flow model appears to account for translocation in the phloem

During sieve tube element development, the tonoplast and much of the cytosol breaks down, allowing the contents of the central vacuole to combine with much of the cytosol to form the sieve tube sap. The sap flows under pressure through the sieve tubes, moving from one sieve tube element to the next by bulk flow through the sieve plates, without crossing a membrane. We need to understand how this pressure is generated in order to understand translocation in the phloem. Two steps in translocation...

Eggs and sperm form through gametogenesis

Spermatogenesis And Oogenesis

Gametogenesis occurs in the gonads, which are testes singular, testis in males and ovaries in females. The tiny gametes of males, called sperm, move by beating their flagella. The larger gametes of females, called eggs or ova singular, ovum , are nonmotile see Figure 20.1 . Gametes are produced from germ cells, which have their origin in the earliest cell divisions of the embryo and remain distinct from the rest of the body. All other cells of the embryo are called somatic cells. Germ cells are...

Identifying Photosynthetic Reactants and Products

Gas Production And Photosynthesis

By the beginning of the nineteenth century, scientists understood the broad outlines of photosynthesis. It was known to use three principal ingredients water, carbon dioxide CO2 , and light and to produce not only carbohydrates but also oxygen gas O2 . Scientists had learned several things The water for photosynthesis in land plants comes primarily from the soil and must travel from the roots to the leaves. Carbon dioxide is taken in, and water and O2 are released, through tiny openings in...

Extracellular Structures

Extracellular Matrix Vessels

Although the plasma membrane is the functional barrier between the inside and the outside of a cell, many structures are produced by cells and secreted to the outside of the plasma membrane, where they play essential roles in protecting, supporting, or attaching cells. Because they are outside the plasma membrane, these structures are said to be extracellular. The peptidoglycan cell wall of bacteria is such an extracellular structure. In eukaryotes, other extracellular structures the cell walls...

Nffi Fertilization is the union of sperm and egg

Acrosomal Process Sperm

f The union of the haploid sperm and the haploid egg 1 f creates a single diploid cell, called a zygote, which will develop into an embryo. Fertilization does more, however, than just restore the full genetic complement of the animal. The events and processes associated with fertilization help eggs and sperm get together, prevent the union of sperm and eggs of different species, guarantee that only one sperm will enter an egg, and activate the egg metabolically. Fertilization involves a...

Glucagon Release

Glucagon Release

b Fuel traffic during the postabsorptive period b Fuel traffic during the postabsorptive period glucagon is released if blood glucose falls too low glucagon is released if blood glucose falls too low Triglycerides and fatty acids Glucose and glycogen Proteins and amino acids 50.21 A Single-Gene Mutation Leads to Obesity in Mice Leptin serves as a negative feedback signal to the brain to limit food intake. The fat cells of the ob ob mouse on the left do not produce leptin. The wild-type mouse...

Evaporation of water is an effective way to lose heat

Animals Hot And Cold Climates

When the environmental temperature rises above the upper critical temperature for an endotherm, overheating becomes a problem. For an exercising animal, overheating can become a problem at even low environmental temperatures. Heavily 41.16 Adaptations to Hot and Cold Climates a The bat-eared fox lives on the dry plains of central and southern Africa. Its large ears serve as heat exchangers, passing heat from the fox's blood to the surrounding air. b The thick fur of the arctic fox provides...

Glial cells are also important components of nervous systems

Schwann Cell

Neurons are not the only type of cell in the nervous system. In fact, there are more glial cells than neurons in the human brain. Like neurons, glial cells come in several forms and have a diversity of functions. Some glial cells physically support and orient the neurons and help them make the right contacts during embryonic development. Other glial cells insulate axons. In the peripheral nervous system, Schwann cells wrap around the axons of neurons, covering them with concentric layers of...

[V h The Mammalian Excretory System

Capillary Adrenal Gland

' The adaptations of mammals and birds that allowed them to produce urine hyperosmotic to their tissue fluid were an important step in vertebrate evolution. These adaptations enabled the excretory system to conserve water while still excreting excess salts and nitrogenous wastes. Mammals and birds have high body temperatures and high metabolic rates, and therefore have the potential for a high rate of water loss. Being able to minimize water loss from their excretory systems made it possible...

General Biology of the Prokaryotes

Gas Vesicles

There are many, many prokaryotes around us everywhere. Although most are so small that we cannot see them with the naked eye, the prokaryotes are the most successful of all creatures on Earth, if success is measured by numbers of individuals. The bacteria in one person's intestinal tract, for example, outnumber all the humans who have ever lived, and even the total number of human cells in their host's body. Some of these bacteria form a thick lining along the intestinal wall. Bacteria and...

Actions

Nicotinic Choline Receptors

The neurotransmitter of vertebrate motor neurons and of some neural pathways in the brain Used in certain neural pathways in the brain. Also found in the peripheral nervous system, where it causes gut muscles to relax and the heart to beat faster A neurotransmitter of the central nervous system A minor neurotransmitter in the brain A neurotransmitter of the central nervous system that is involved in many systems, including pain control, sleep wake control, and mood Co-released with many...

Blood flows from right heart to lungs to left heart to body

Heart Pressure Left Right Ventricle

Let's follow the circulation of the blood through the heart, starting in the right heart. The right atrium receives deoxy-genated blood from the superior upper vena cava and the inferior lower vena cava see Figure 49.3 , large veins that collect blood from the upper and lower body, respectively. contract, the atrioventricular valves close, and pressure in the ventricles builds up until the aortic and pulmonary valves open. 3 Blood is pumped out of the ventricles and into the aorta and pulmonary...

The timing of a genes expression can affect morphology

Bmp4 Apoptosis

Modularity also allows the relative timing of two different developmental processes to shift independently of one another, a process called heterochrony. That is, the genes regulating Beetle Springtail Shrimp Spider Centipede Onycophoran In the insect lineage, a mutation in the Ubx homeotic gene prevents legs from forming in the abdominal segments. In the insect lineage, a mutation in the Ubx homeotic gene prevents legs from forming in the abdominal segments. Most arthropods have legs growing...

Which Biome Is Dominated By Low-growing Shrubs And Trees That Have Tough Evergreen Leaves

Animals From The Semairid Biome

Low stature shrubs and herbaceous plants Plants Extremely high in South Africa and Australia Animals Rich in rodents and reptiles very rich in insects, especially bees Fynbos vegetation, Cape of Good Hope, South Africa Fynbos vegetation, Cape of Good Hope, South Africa The chaparral climate is dry and pleasant The chaparral biome is found on the west sides of continents at moderate latitudes around 30o , where cool ocean waters flow offshore. Winters in this biome are cool and wet summers are...

Most chemical digestion occurs in the small intestine

Liver And Bile Secretion

In the small intestine, the digestion of carbohydrates and proteins continues, and the digestion of fats and the absorption of nutrients begin. The small intestine takes its name from its diameter it is in fact very large organ, about 3 meters long in an adult. Because of its length, and because of the folds, villi, and microvilli of its lining, its inner surface area is enormous about 550 m2, or roughly the size of a tennis court. Across this surface, the small intestine absorbs all the...

Start

Conjugation Paramecium

After a mosquito ingests blood, male and female gametocytes develop into gametes, which fuse. The resulting zygote, the only diploid stage in the life cycle, enters the mosquito's gut wall and forms a cyst. After a mosquito ingests blood, male and female gametocytes develop into gametes, which fuse. The resulting zygote, the only diploid stage in the life cycle, enters the mosquito's gut wall and forms a cyst. 3 Within the cyst, the zygote gives rise to sporozoites. 5 The mosquito injects...

The Evolution of Genome Size

Coli Genome Size

We can now consider what determines the sizes of the genomes of different organisms. As organisms evolved to become more complex, how did the number of functional genes increase so that the organisms could carry out the greater variety of metabolic activities associated with that complexity Complex organisms have more DNA than do simpler ones As we saw in Chapters 13 and 14, genome size varies tremendously among organisms. The first pattern to be detected was that genome sizes are generally...

Reproductive technologies help solve problems of infertility

There are many reasons why a man and woman may not be able to have children. The man's rate of sperm production may be low, or his sperm may lack motility. The mucus in the woman's reproductive tract may be thick and not conducive to sperm reaching the oviducts. Structural problems may also exist, such as blockage of the oviducts by scar tissue or by endometriosis, a proliferation of endometrial cells outside of the uterus. In some cases, treatment with powerful chemicals to cure cancer damages...

Nuclear Transplantation

Nuclear Transplantation Sheep

Question Are differentiated animal cells totipotent An egg is removed from a Scottish blackface ewe. Question Are differentiated animal cells totipotent An egg is removed from a Scottish blackface ewe. 8 The embryo develops and Dolly is born. Dorset sheep, genetically identical to 1 Conclusion Differentiated animal cells are totipotent in nuclear transplant experiments. 8 The embryo develops and Dolly is born. Dorset sheep, genetically identical to 1 Conclusion Differentiated animal cells are...

Imbalance

Osteoclast Calcitonin

Ca2 concentration greater or less than 11 mg ml blood Blood Ca2 high thyroid secretes calcitonin Blood Ca2 low parathyroids secrete parathormone Blood Ca2 low parathyroids secrete parathormone Calcitonin stimulates osteoblasts to take up Ca2 from blood and lay down new bone. Parathormone stimulates osteoclasts to resorb bone and return Ca2 to blood it also stimulates the absorption of calcium from the intestines and decreased loss of calcium from the kidneys. 42.9 Hormonal Regulation of Calcium...

Speciation Is An Important Component Of Evolution Because It

A. actually interbreeding natural populations that are reproductively isolated from other such groups. b. potentially interbreeding natural populations that are reproductively isolated from other such groups. c. actually or potentially interbreeding natural populations that are reproductively isolated from other such groups. d. actually or potentially interbreeding natural populations that are reproductively connected to other such groups. e. actually interbreeding natural populations that are...

Spraying Dwarf Plants With Gibberelin

Plants Without Gibberellins

Gibberellin Aj important in stem growth Gibberellin A3 commercially available In 1809, the study of the gibberellins began indirectly with observations of the bakanae, or foolish seedling, disease of rice. Seedlings affected by this disease grow tall more rapidly than their healthy neighbors, but this rapid growth gives rise to spindly plants that die before producing seeds the rice grains used for food . The disease has had considerable economic impacts in several parts of the world. It is...

Distal Convoluted Tubule Function

Medullary Venule

Urine leaves the kidney from the inner surface of the medulla and is collected in the ureter. Urine leaves the kidney from the inner surface of the medulla and is collected in the ureter. fytyi 51.9 The Human Excretory System a The human kidneys If fi are positioned in the upper dorsal region of the abdominal V j cavity, ft The human kidney has a regular internal tissue ' structure that is the basis for its function, c The glomeruli and the proximal and distal convoluted tubules are located in...

Leaves are the primary sites of photosynthesis

Types Leaf Divisions

In gymnosperms and most flowering plants, the leaves are responsible for most of the plant's photosynthesis, producing energy-rich organic molecules and releasing oxygen gas. In certain plants, the leaves are highly modified for more specialized functions, as we will see below. As photosynthetic organs, leaves are marvelously adapted for gathering light. Typically, the blade of a leaf is a thin, flat structure attached to the stem by a stalk called a petiole. During the daytime, the leaf blade...

Light Absorption Optic Nerve

Photoreceptor Rhodopsin Sodium Channels

A bright light stimulus results in a strong hyperpolarization. opsin pass through several unstable intermediate stages. One of these stages is known as photoexcited rhodopsin because it triggers a cascade of reactions that result in the alteration of membrane potential that is the photoreceptor cell's response to light. To get a better idea of how rhodopsin alters the membrane potential of a photoreceptor cell and how that photoreceptor cell signals that it has been stimulated by light, let's...

Self Quiz

Which of the following describes the route of sensory information from the foot to the brain a. Ventral horn, spinal cord, medulla, cerebellum, midbrain, thalamus, parietal cortex b. Dorsal horn, spinal cord, medulla, pons, midbrain, hypothalamus, frontal cortex c. Dorsal horn, spinal cord, medulla, pons, midbrain, thalamus, parietal cortex d. Ventral horn, spinal cord, pons, cerebellum, midbrain, thalamus, parietal cortex e. Dorsal horn, spinal cord, medulla, pons, midbrain, thalamus,...

Tissues Organs and Organ Systems

Four Types Tissue

Cells are the basic building blocks of multicellular animals. When cells with the same characteristics or specializations are grouped together, they form a tissue. There are four basic types of tissues epithelial, connective, muscle, and nervous but there are variations on each basic type. An organ is usually made up of several different tissue types Figure 41.2 . 41.2 Four Types of Tissue All cells can be classified into one of four tissue types. An organ such as the stomach is made up of...

Environments and animals can be classified in terms of salts and water

Salt Gland Marine Birds

The salt concentration, or osmolarity, of ocean water is about 1,070 milliosmoles liter mosm l , and fresh water is generally between 1 and 10 mosm l. Aquatic environments grade continuously from fresh to extremely salty. Consider a place where a river enters the sea through a bay or a marsh. Aquatic environments within that bay or marsh range in os-molarity from that of the fresh water of the river to that of the open sea. Evaporating tide pools can reach an even greater osmolarity than...

Uh Endocytosis and Exocytosis

Sodium Ion Transport

1 f Macromolecules such as proteins, polysaccharides, and nucleic acids are simply too large and too charged or polar to pass through membranes. This is a fortunate property. Think of the consequences if these molecules could diffuse out of cells A red blood cell would not retain its hemoglobin On the other hand, cells must sometimes take up or secrete intact large molecules. As we saw in Chapter 4, this can be done by means of vesicles that either pinch off from the plasma membrane and enter...

Human brains became larger

The earliest members of Homo sapiens had larger brains than members of the earlier species of Homo. Brain size in the lineage increased rapidly, reaching modern size by about 160,000 years ago. This striking change was probably favored by an increasingly complex social life. The ability of group members to communicate with one another would have been valuable in cooperative hunting and gathering and for improving one's status in the complex social interactions that must have characterized early...

. Negative Feedback A. Is Not As Common As Positive Feedback In Regulatory Systems Of The Body. B. Is A Feature Of

If the Q10 of the metabolic rate of an animal is 2, then a. the animal is better acclimatized to a cold environment than if its Q10 is 3. c. the animal consumes half as much oxygen per hour at 20 C as it does at 30 C. d. the animal's metabolic rate is not at basal levels. e. the animal produces twice as much heat at 20 C as it does at 30 C. 2. Which statement about brown fat is true a. It produces heat without producing ATP. b. It insulates animals acclimatized to cold. c. It is a major...

Autoregulation matches local blood flow to local need

Vein Smooth Muscles Blood Movement

The autoregulatory mechanisms that adjust the flow of blood to a tissue are local mechanisms, but they can be influenced by the nervous system and by certain hormones. Blood flow through a capillary bed is controlled by the constriction of smooth muscle in the arteries and arterioles. 49.17 Local Control of Blood Flow Low O2 concentrations or high levels of metabolic by-products cause the smooth muscle of the arteries and arterioles to relax, thus increasing the supply of blood to the capillary...

Birds Make Extremely Efficient Use Of Air. This System Enables Them To Fly Even At An Altitude Of 8 000 Meters Where

Make Water Column Barometer

And so back up the gradual slopes, the wind behind me. A much greater effort this, stopping every few yards with a slight anxiety lest I should not make the distance. As I approached the tents, I was astonished to see a bird, a chough, strutting about on the stones near me. During this day, too, Charles Evans saw what must have been a migration of small grey birds. Neither of us had thought to find any signs of life as high as this. Sir John Hunt, Ascent of Everest, 1953 In his book about the...

A hierarchy of meristems generates a plants body

Meristems Plants Lateral Apical

Apical meristems give rise to the primary plant body, which is the entire body of many plants. Lateral meristems give rise to the secondary plant body. The stems and roots of some plants most obviously trees form wood and become thick it is the lateral meristems that give rise to the tissues responsible for this thickening. apical meristems. Apical meristems are located at the tips of roots and stems and in buds. They extend the plant body by producing the cells that subsequently expand and...

Possession Of Which Feature Is Not Desirable In A Vector For Gene Cloning

B. cleave DNA at highly specific recognition sequences. c. are inserted into bacteria by bacteriophages. d. are made only by eukaryotic cells. e. add methyl groups to specific DNA sequences. 2. When fragments of DNA of different sizes are placed in an electrical field, a. the smaller pieces migrate most quickly to the positive pole. b. the larger pieces migrate most quickly toward the positive pole. c. the smaller pieces migrate most quickly toward the negative pole. d. the larger pieces...

Steps Of Muscle Contraction

Myofibrils Micrograph

RESULTS Autonomic neurotransmitters alter membrane resting potential and thereby determine the rate that smooth muscle cells fire action potentials. Conclusion Smooth muscle contraction is stimulated by stretch and by the parasympathetic neurotransmitter acetylcholine. 47.2 Mechanisms of Smooth Muscle Activation Stretching depolarizes the membrane of smooth muscle cells, and this depolarization causes action potentials that activate the contractile mechanism.The neurotransmitters acetylcholine...

The Cytoskeleton

Components Cytoskeleton

In addition to its many membrane-enclosed organelles, the eukaryotic cytoplasm contains a set of long, thin fibers called the cytoskeleton. The cytoskeleton fills at least three important roles It maintains cell shape and support. It provides for various types of cellular movement. Some of its fibers act as tracks or supports for motor proteins, which help move things within the cell. In the discussion that follows, we'll look at three components of the cytoskeleton microfilaments, intermediate...

Functional Subsystems of the Nervous System

Gyri Function

We have just surveyed the development of the nervous system in terms of anatomically distinct structures. At any one time, these various structures are engaged in many simultaneous tasks a property known as parallel processing of information. Specific tasks are carried out by subsystems that may involve several different anatomical regions or structures of the nervous system. We will now examine several of these functional subsystems. The spinal cord receives and processes information from the...

Ectotherms and endotherms respond differently to changes in environmental temperature

A small lizard can serve as an example of an ectotherm. We can compare it with a mouse, which is an endotherm of the same body size. We can put each animal in a closed chamber and measure its body temperature and metabolic rate as we change the temperature of the chamber from 0 C to 35 C. The results obtained from the two species differ. The body temperature of the lizard equilibrates with that of the chamber, whereas the body temperature of the mouse remains at 37 C Figure 41.7a . The...

Cytoplasmic Determinants

Embryo Cell Stage

The embryo is bisected horizontally, separating animal pole cells from vegetal pole cells. The embryo is bisected vertically, leaving each half with both animal and vegetal cells. Cells remain Abnormal larva Normal, but small, larvae embryonic Conclusion The animal and vegetal pole halves differ in their developmental potential. Cells remain Abnormal larva Normal, but small, larvae embryonic Conclusion The animal and vegetal pole halves differ in their developmental potential. 19.7 Asymmetry in...

Membrane Composition and Structure

Integral Membrane Proteins

The physical organization and functioning of all biological membranes depend on their constituents lipids, proteins, and carbohydrates. The lipids establish the physical integrity of the membrane Stephen Hawking The effects of motor neuron disease have confined the famous physicist to a wheelchair. A major cellular manifestation of this disease is the lack of ability of the nerve cells to stimulate the opening of channels through muscle cell membranes that would result in normal muscle...

Xylem transports water from roots to stems and leaves

Xylem Tracheids And Vessels

The xylem of tracheophytes conducts water from roots to aboveground plant parts. It contains conducting cells called tracheary elements, which undergo programmed cell death before they assume their function of transporting water and dissolved minerals. There are two types of tracheary elements. The evolutionarily more ancient tracheary elements, found in gymnosperms and other tracheophytes, are tracheids spindle-shaped cells interconnected by numerous pits in their cell walls Figure 35.9e ....

Ftiii The hormones insulin and glucagon I 0 control fuel metabolism

' f During the absorptive period, blood glucose levels rise as carbohydrates are digested and absorbed. During this time, the P cells of the pancreas release a hormone called insulin see Chapter 42 . Insulin plays a major role in directing glucose to where it will be used or stored. Insulin enhances the uptake of glucose from the blood and its conversion to glycogen by liver and muscle cells. It stimulates fat cells to take up glucose from the blood and convert it to stored fat, and it...

Uptake of mineral ions requires membrane transport proteins

Buildup Muscles

Mineral ions, which carry electric charges, generally cannot move across a membrane unless they are aided by transport proteins explained in Chapter 5 . When the concentration of these charged ions in the soil is greater than that in the plant, ion channels and carrier proteins can move them into the plant by facilitated diffusion, which is a passive process. The concentrations of most ions in the soil solution, however, are lower than those required inside the plant. Thus the plant must take...

Cell Fractionation

Lamina Nuclear

The cell homogenate contains large and small organelles._ The heaviest organelles can be removed and the remaining suspension re-centrifuged until the next heaviest organelles reach the bottom of the tube. 4.8 Cell Fractionation The organelles of cells can be separated from one another after cells are broken open and centrifuged. The heaviest organelles can be removed and the remaining suspension re-centrifuged until the next heaviest organelles reach the bottom of the tube. The nuclear lamina...

Neurulation Initiating the Nervous System

Gastrulation produces an embryo with three germ layers that are positioned to influence one another through inductive interactions. During the next phase of development, called organogenesis, many organs and organ systems develop simultaneously and in coordination with one another. An early process of organogenesis that is directly related to gastrula-tion is neurulation, the initiation of the nervous system in vertebrates . We will examine this event in the amphibian embryo, but it occurs in a...

Chemical digestion begins in the mouth and the stomach

Gastric Glands

The enzyme amylase is secreted by the salivary glands and mixed with food as it is chewed. Amylase hydrolyzes the bonds between the glucose monomers that make up starch molecules. The action of amylase is what makes a chewed piece of bread or cracker taste slightly sweet if you hold it in your mouth long enough. Most vertebrates can rapidly consume a large volume of food, but digesting that food is a slower process. The stomach stores the consumed food until it can be digested. The se The...

Biological Evolution Changes over Billions of Years

Mammalian Forelimbs

Long before the mechanisms of biological evolution were understood, some people realized that organisms had changed over time and that living organisms had evolved from organisms that were no longer alive on Earth. In the 1760s, the French naturalist Count George-Louis Leclerc de Buffon 1707-1788 wrote his Natural History of Animals, which contained a clear statement of the possibility of evolution. Buffon observed that the limb bones of all mammals were remarkably similar in many details...

Cell Recognition and Adhesion

Complementary Proteins

Some organisms, such as bacteria, are unicellular that is, the entire organism is a single cell. Others, such as plants and animals, are multicellular composed of many cells. Often these cells exist in specialized blocks of cells with similar functions, called tissues. Your body has about 60 trillion cells, arranged in different kinds of tissues such as muscle, nerve, skin, and so forth. Two processes allow cells to arrange themselves in groups Cell recognition, in which one cell specifically...

Development Begins with Fertilization

Human Fertilization

Fertilization is the union of a haploid sperm and a haploid egg to produce a diploid zygote. Fertilization does more, however, than just restore a full complement of maternal and paternal genes. The entry of a sperm into an egg activates the egg metabolically and initiates the rapid series of cell divisions that produce a multicellular embryo. Also, in many species, the point of entry of the sperm creates an asymmetry in the radially symmetrical egg. This asymmetry is the initiating event that...

Parenchyma cells are alive when they perform their functions

Sclerenchyma Cells

The most numerous cell type in young plants is the parenchyma cell Figure 35.9a . Parenchyma cells usually have thin walls, consisting only of a primary wall and the shared middle lamella. Many parenchyma cells have shapes with multiple faces. Most have large central vacuoles. 35.8 Pits Secondary walls may be interrupted by pits,which allow the passage of water and other materials between cells. 35.8 Pits Secondary walls may be interrupted by pits,which allow the passage of water and other...

The pressure flow model has been experimentally tested

Xylem Pressure Flow

The pressure flow model was first proposed more than half a century ago, but some of its features are still being debated. M Transpiration pulls water up xylem vessels. I Source cells load sucrose into phloem sieve tubes, reducing their water potential .so water is taken up from xylem vessels by osmosis. Internal pressure differences drive the sap down the sieve tube to sink cells. Sucrose is unloaded into sink cells.

Materials are exchanged in capillary beds by filtration osmosis and diffusion

Red Cells Squeezing Through Capillary

The walls of capillaries are made of a single layer of thin en-dothelial cells. In most tissues of the body other than the brain, capillaries have tiny holes called fenestrations Latin, anatomical characteristics of blood vessels match their functions. Red blood cells must pass through capillaries in single file. Red blood cells must pass through capillaries in single file. 49.11 A Narrow Lane Capillaries have a very small diameter, and blood flows through them slowly. windows . Capillaries are...

The arrival of a nerve impulse causes the release of neurotransmitter

Nerve Impulse And Acetylcholine

What causes the presynaptic membrane to release neurotransmitter Neurotransmitter is released when a nerve impulse arrives at the axon terminal. The presynaptic membrane contains voltage-gated calcium channels. When a nerve impulse depolarizes the axon terminal, it causes these channels to open see Figure 44.13 . Because Ca2 concentra The acetylcholine receptor-mediated channel is normally closed. When ACh binds at specific sites on the receptor, the channel opens, allowing Na to enter the...

Both marine and terrestrial vertebrates must conserve water

Malpighian Tubules

Some paleontologists believe that the immediate ancestors of the vertebrates lived in fresh water. If that is true, the nephron would have evolved as a structure to excrete excess water. Indeed, the Uric acid precipitates in rectum and is secreted. Uric acid precipitates in rectum and is secreted. Semisolid wastes including uric acid Uric acid, Na , and K are transported into the Malpighian tubules H2O follows. Semisolid wastes including uric acid Uric acid, Na , and K are transported into the...

Organelles that Process Energy

Figure Chloroplast Structure

A cell uses energy to synthesize cell-specific materials that it can use for activities such as growth, reproduction, and movement. Energy is transformed from one form to another in mitochondria found in all eukaryotic cells and in chloro-plasts found in eukaryotic cells that harvest energy from sunlight . In contrast, energy transformations in prokaryotic cells are associated with enzymes attached to the inner surface of the plasma membrane or extensions of the plasma membrane that protrude...

Nitrogenase catalyzes nitrogen fixation

Plant Root Bacteroid Nitrogenase

Nitrogen fixation is the reduction of nitrogen gas. It proceeds by the stepwise addition of three pairs of hydrogen atoms to N2 Figure 37.6 . In addition to N2, these reactions require The enzyme nitrogenase binds a molecule of nitrogen gas. 2 A reducing agent transfers three successive pairs of hydrogen atoms to N2. 37.6 Nitrogenase Fixes Nitrogen Throughout the chemical reactions of nitrogen fixation, the reactants are bound to the enzyme nitrogenase. A reducing agent transfers hydrogen atoms...

Making Carbohydrate from CO2 The Calvin Benson Cycle

At the start of this chapter we identified two distinct metabolic pathways operating in photosynthesis. We have now discussed the first pathway the light reactions, which use light energy to produce ATP and NADPH H in the chloroplasts of green plants. The second pathway, the Calvin-Benson cycle, uses this ATP and NADPH H to incorporate CO2 into carbohydrates. Most of the enzymes that catalyze the reactions of the Calvin-Benson cycle are dissolved in the chloroplast stroma the soup outside the...

Many stems and roots undergo secondary growth

Xylem Cell

Some stems and roots remain slender and show little or no secondary growth. However, in many eudicots, secondary growth thickens stems and roots considerably. This process gives rise to wood and bark, and it makes the support of tall trees possible. Secondary growth results from the activity of the two lateral meristems vascular cambium and cork cambium see Figure 35.13 . Vascular cambium consists of cells that divide to produce secondary xylem and phloem cells, while cork cambium produces...

Detecting Stimuli that Distort Membranes

Transduction Sound Auditory Nerve

Mechanoreceptors are cells that are sensitive to mechanical forces. Physical distortion of a mechanoreceptor's plasma membrane causes ion channels to open, altering the membrane potential of the cell, which in turn leads to the generation of action potentials. The rate of action potentials tells the CNS the strength of the stimulus exciting the mechanorecep-tor. Mechanoreceptor cells are involved in many sensory systems, ranging from skin sensations to sensing blood pressure. Sensory cells use...

Diversity in the Kingdom Fungi

Rhizopus Life Cycle Figure

In this section on fungal diversity, we'll consider four phyla Chytridiomycota, Zygomycota, Ascomycota, and Basid-iomycota Figure 31.6 Table 31.1 . The first two groups are probably not clades, but the Ascomycota and Basidiomycota are clades. Chytrids probably resemble the ancestral fungi The earliest-diverging fungal group is the chytrids phylum Chytridiomycota . These aquatic microorganisms were formerly classified with the pro- tists. However, morphological cell walls Basidiomycota I that...

Melatonin is involved in biological rhythms and photoperiodicity

The pineal gland is situated between the two hemispheres of the brain and is connected to the brain by a little stalk. It produces the hormone melatonin from the amino acid tryp-tophan. The release of melatonin by the pineal occurs in the dark and therefore marks the length of the night. Exposure to light inhibits the release of melatonin. In various vertebrates, melatonin is involved in biological rhythms, including photoperiodicity the phenomenon whereby seasonal changes in day length cause...

Fertilization Of Flowers

Sequence Fertilisation Flowers

30.7 A Generalized Flower Not all flowers possess all the structures shown here, but they must possess a stamen bearing microsporangia , a pistil containing megasporangia , or both in order to play their role in reproduction. Flowers that have both, as this one does, are referred to as perfect. mens, and carpels which are referred to as the floral organs see Figure 19.12 are usually positioned in circular arrangements or whorls and attached to a central stalk called the receptacle. The...

Eukarya

Archaea High Pressure Lovers

Three of the bacterial groups that may have branched out earliest during bacterial evolution are all thermophiles heat lovers , as are the most ancient of the archaea. This observation supports the hypothesis that the first living organisms were thermophiles that appeared in an environment much hotter than those that predominate today. The Proteobacteria are a large and diverse group By far the largest group of bacteria, in terms of numbers of described species, is the proteobacteria, sometimes...

The pituitary is closely associated with the brain

Posterior Pituitary And Hypothalamus

The pituitary gland sits in a depression at the bottom of the skull just over the back of the roof of the mouth Figure 42.5 . It is attached by a stalk to the part of the brain called the hypothalamus, which is involved in many homeostatic regulatory systems see Chapter 41 . The pituitary has two distinct parts that have different functions and separate origins during development. The anterior pituitary originates as an outpocketing of the embryonic mouth cavity, and the posterior pituitary...

Heart Rate Chemoreceptor

Regulating Blood Pressure

Circulating renin activates angiotensin 49.18 Control of Blood Pressure through Vascular Resistance A drop in arterial pressure reduces blood flow to tissues,resulting in local accumulation of metabolic wastes.This change in the extracellular environment stimulates autoregulatory opening of the arteries and would lead to a further decrease in central blood pressure if this were not prevented by the negative feedback mechanisms shown in this diagram, which work by promoting the constriction of...

Ribbon worms are unsegmented

Earthworm Muscular Circular

The carnivorous ribbon worms phylum Nemertea are dorsoventrally flattened. They have nervous and excretory systems similar to those of flatworms, but unlike flatworms, they have a complete digestive tract with a mouth at one end and an anus at the other. Food moves in one direction through the digestive tract and is acted on by a series of digestive enzymes. Small ribbon worms move by beating their cilia. Larger ones employ waves of muscle contraction to move over the surface of sediments or to...