Funguslike Protists

Biologists recognize two groups of funguslike protists slime molds and water molds. Slime molds are typically found on moist, decaying matter. They appear as glistening white, yellow, or red masses of slime, as shown in Figure 25-14. Slime molds have life cycles in which they spend part of their lives in a mobile, amoebalike feeding form, consuming organic matter and bacteria much as protozoa do. However, these protists have a stationary reproductive stage in which they produce a funguslike,...

Understanding Key Concepts

Identify six key characteristics of mammals. 5. Relate the characteristics of therapsids and synapsids to those of mammals. 6. Relate the evolution of mammals to the mass extinction of Cretaceous reptiles. 7. Compare the costs and benefits of endothermy for mammals. 8. Explain how the structure of the mammalian heart supports endothermy. 9. Describe the important adaptations of the teeth of mammals. 10. Compare the teeth of rodents to those of lagomorphs. 11. Describe two mammalian adaptations...

Receptors and Sense Organs

A sensory receptor is a neuron that detects stimuli. There are many kinds of sensory receptors. These receptors can be categorized based on the type of stimuli to which they respond. Mechanoreceptors respond to movement, pressure, and tension. Photoreceptors respond to variations in light. Chemoreceptors respond to chemicals. Thermoreceptors respond to changes in temperature. Pain receptors respond to tissue damage. Sensory receptors are found in higher concentrations in the sense organs than...

Chapter Review

For each pair of terms, explain how the meanings of the terms differ. a. macrophage and natural killer cell 2. Explain the relationship between HIV and AIDS. 3. Use the following terms in the same sentence cell-mediated immune response, helper T cell, cytotoxic T cell, and interleukin-2. 4. Word Roots and Origins The word pathogen is derived from the Greek pathos, which means suffering or disease, and -gen, which means to produce. Using this information, explain why the term pathogen is a good...

Vitamins Minerals And Water

Vitamins, minerals, and water are nutrients that do not provide energy but are required for proper functioning of the body. Vitamins work as coenzymes to enhance enzyme activity. Minerals are necessary for making certain body structures, for normal nerve and muscle function, and for maintaining osmotic balance. Water transports gases, nutrients, and waste is a reagent in some of the body's chemical reactions and regulates body temperature. Table 48-1 summarizes the sources of vitamins and their...

Electron Transport Chain And Chemiosmosis

The electron transport chain, linked with chemiosmosis, constitutes the second stage of aerobic respiration. Recall that the electron transport chain is a series of molecules in a membrane that transfer electrons from one molecule to another. In eukaryotic cells, the electron transport chain and the enzyme ATP synthase are embedded in the inner membrane of the mitochondrion in folds called cristae. In prokaryotes, the electron transport chain is in the cell membrane. ATP is produced by the...

Dna

Prokaryotic DNA is a single closed loop of double-stranded DNA attached at one point to the cell membrane. Unlike eukaryotic DNA, prokaryotic DNA is not enclosed in a nucleus. Along with this single main chromosome, some prokaryotes have plasmids. Plasmids are small, circular, self-replicating loops of double-stranded DNA. Plasmids are usually not necessary for the cell's growth and reproduction, but some plasmids carry genes that enable the bacterium to cause disease. Other plasmids carry...

Part B

Compare the contents of each cup every day for two weeks, and record the appearance of the wheat seedlings in your data tables. If you are unable to observe your seedlings over the weekend, be sure to note in your data table that no observations were made on those days. 12. Each time that you observe the seedlings after they have begun to grow, measure their height and record the average height of the seedlings in each cup in your data tables. To find the average height for one cup, add the...

Alcohol

For people age 21 and older, alcohol is a legal drug. Alcohol is a depressant, a drug that decreases the activity of the central nervous system. Alcohol increases circulation to the skin, decreases blood flow to internal organs, and lowers body temperature. Alcohol causes the kidneys to excrete more water, which can cause dehydration. As drinking continues, judgment and coordination become impaired, speech slurs, and reaction time lengthens. Respiration rate slows after an initial increase....

Evidence of Evolution

Many kinds of evidence give insight into the history of life on Earth and the patterns of change among organisms. Fossils that are different from organisms living today are strong evidence that organisms on Earth can change over time. But evidence of evolution is also found inside living organisms. These fossils of pterosaur bones (a), fern leaves (b), and trilobite exoskeletons (c) were buried in ancient sediment. The insect (d) was trapped in ancient tree sap. In each case, the surrounding...

The Immune System

The immune system, the cells and tissues that recognize and attack foreign substances in the body, provides the body's specific defenses. The immune system fights pathogens and helps to stop the growth and spread of cancers. The immune system is made up of several tissues and white blood cells. The components of the immune system, shown in Figure 47-5, are found throughout the body. The tissues include the bone marrow, thymus, lymph nodes, spleen, tonsils, and adenoids. The white blood cells of...

The Niche

Species do not use or occupy all parts of their habitat at once. The specific role, or way of life, of a species within its environment is its niche (NICH). The niche includes the range of conditions that the species can tolerate, the resources it uses, the methods by which it obtains resources, the number of offspring it has, its time of reproduction, and all other interactions with its environment. Parts of a lion's niche are shown in Figure 18-6. Generalists are species with broad niches...

Domain Eukarya

Kingdom Protista is a diverse group of eukaryotes that are not plants, fungi, or animals. Traditionally, species have been classified in Protista whenever their characteristics do not clearly match with those of one of the other eukaryotic kingdoms. Because protists are not defined clearly, are so diverse, and are so poorly understood, the classification of protists is problematic. Many scientists have proposed groupings and names that differ from those listed here. In fact, three or more new...

1

The realized niche of the Chthamalus barnacle species is smaller than its fundamental niche because of competition from the Semibalanus species. Although Chthamalus can survive at all levels of the intertidal zone, it is usually crowded out at the lower level by the faster-growing Semibalanus. But Semibalanus cannot survive in the upper level, which is left dry for longer periods. www.scilinks.org Topic Competition Keyword HM60326 IM C National Science JI v ft Taachers Association...

Adapting To Land

Although life had flourished in the oceans for more than 3 billion years, no organisms lived on land until about 475 million years ago, when a layer of ozone formed. The ozone protected organisms from the sun's ultraviolet radiation. Eventually, small club-shaped plants began to grow in the mud at the water's edge. Three adaptations allowed plants to thrive on land the ability to prevent water loss, the ability to reproduce in the absence of water, and the ability to absorb and transport...

The Life Cycle Of Ferns

The life cycle of a typical fern, shown in Figure 30-2, is similar to the moss life cycle. Like mosses, most ferns are homosporous. And as in mosses, the fern sporophyte grows from the gametophyte. But in the fern life cycle, the sporophyte, not the gametophyte, is the dominant generation. Fern gametophytes are tiny (about 10 mm, or 0.5 in., in diameter), flat plants that are anchored to the soil by rhizoids. Both antheridia and archegonia may form on the lower surface of a fern gametophyte....

Protists In Research

Research on protists has helped biologists understand a number of fundamental cellular functions, such as cell movement. For example, individual cells of the cellular slime mold Dictyostelium discoidum move toward a source of AMP, a precursor to the energy-storage molecule ATP. These cells crawl using amoeboid movement, shown in Figure 25-18. Researchers are interested in learning how Dictyostelium cells can recognize AMP and crawl toward it, a process called chemotaxis. The researchers think...

Forests

Scientists have classified up to 26 types of forests worldwide. Forest biomes are divided into three main types tropical, temperate, and boreal forests, or taiga. Tropical forests occur near the equator, in the region between 23.5 N and 23.5 S, known as the tropics. This region includes parts of Asia, Africa, South America, and Central America. Stable temperature and abundant rainfall make tropical forests the most productive biome type. Tropical forests have only two seasons one wet and one...

Section I Review

Explain how two populations can be the same size but have different densities. 2. Explain how uniform distributions could result from social interactions between individuals. 3. How can the dispersion of one population be described as both uniform and clumped 4. Explain what birth rate and death rate mean. 5. In Figure 19-4, which country has a higher percentage of elderly people 6. Compare the three types of survivorship curves.

Transport of Oxygen

When oxygen diffuses into the blood, only a small amount remains dissolved in the plasma. Most of the oxygen 95 to 98 percent moves into the red blood cells, where it combines with hemoglobin, an iron-containing protein. Each hemoglobin molecule contains four iron atoms. Each iron atom can bind to one oxygen molecule. Thus, one hemoglobin molecule can carry up to four molecules of oxygen. There are about 250 million hemoglobin molecules in each red blood cell. When oxygenated blood reaches body...

Vocabulary

Immune response helper T cell cell-mediated immune response cytotoxic T cell humoral immune response plasma cell antibody memory cell immunity vaccination allergy asthma The cells and tissues of the immune system recognize and attack foreign substances in the body. from the Greek anti, meaning against,' and gen, meaning producing Lymph nodes, located throughout the body along the vessels of the lymphatic system, contain lymphocytes. (Recall that the lymphatic system gathers and filters the...

Adrenal Glands

One adrenal gland (uh-DREE-nuhl gland) is located above each kidney, as shown in Figure 50-6. Each adrenal gland has an inner core, the medulla, and an outer layer, the cortex. The medulla and cortex function as separate endocrine glands. Secretion of hormones in the medulla is controlled by the nervous system, whereas hormones in the anterior pituitary regulate secretion of hormones in the cortex. The adrenal medulla produces two amino acid-based hormones epinephrine (EP-uh-NEF-rin) and...

Rna Structure And Function

Like DNA, RNA is a nucleic acid made up of nucleotides. However, as shown in Figure 10-13, the structure of RNA differs from that of DNA in four basic ways. First, RNA contains the sugar ribose, not the sugar deoxyribose found in DNA. Second, RNA contains the nitrogenous base uracil instead of the nitrogenous base thymine found in DNA. Third, RNA is usually single stranded rather than double stranded like DNA. However, within a single-stranded RNA molecule, some regions fold to form short...

White Blood Cells

White blood cells, or leukocytes (LOO-kuh-siets), help defend the body against disease. They are formed in the red marrow, but some must travel to lymph nodes, tonsils, the thymus, or the spleen to mature. White blood cells are larger than red blood cells and significantly less plentiful. Each cubic millimeter of blood normally contains about 4 million red blood cells and 7,000 white blood cells. White blood cells can squeeze their way through openings in the walls of blood vessels and into the...

Gene Expression In Prokaryotes

Scientists first studied gene expression in prokaryotes. Much of our initial knowledge of gene expression came from the work of French scientists Fran ois Jacob (1920 ) and Jacques Monod (1910-1976) at the Pasteur Institute in Paris. In the early 1960s, Jacob and Monod discovered how genes control the metabolism of the sugar lactose in Escherichia coli, a bacterium that lives in the intestines of mammals. Jacob and Monod won the Nobel Prize in 1965 for their discoveries. Copyright by Hot,...

Freshwater Zones

Low levels of dissolved salts characterize freshwater ecosystems. The salt content of fresh water is about 0.005 percent. Examples of freshwater ecosystems include lakes, ponds, freshwater wetlands, clear mountain streams, and slow, sediment-rich rivers. Ecologists divide lakes and ponds into two categories. Eutrophic (yoo-TRAHF-ik) lakes are rich in organic matter and vegetation, so the waters are relatively murky. As the number of plants and algae in a lake grows, the number of bacteria...

Effects Of Gene Location

When Morgan was doing his research with fruit flies, one of the lab members noticed that a single male fruit fly had white eyes instead of the red eyes that are normally found in the flies. Morgan crossed this white-eyed male with a normal red-eyed female, and found that all the F1 offspring had red eyes, as shown in Figure 12-3a. This demonstrated that the red-eye trait is dominant to the white-eye trait. Morgan next crossed F1 males with F1 females, as shown in Figure 12-3b. The resulting F2...

Standardized Test Preparation

DIRECTIONS Choose the letter of the answer choice that best answers the question. 1. The eukaryotic nucleus houses all of the following except the 2. Which structure contributes to support and movement within a cell 3. Which of the following statements about RNA is true A. RNA is found only in proteins. B. RNA is found only in the nucleus. C. RNA is found only in the cytoplasm. D. RNA is found in the nucleus and cytoplasm. INTERPRETING GRAPHICS The graph below shows the relationship between...

Hearing And Balance

The ear performs two main functions detecting sound and maintaining balance. The fleshy structure of the external ear directs sound vibrations into the ear. As Figure 49-10 shows, the auditory canal connects the external ear with the tympanic (tim-PAN-ik) membrane, or eardrum. Vibrations in the air of the auditory canal cause the tympanic membrane to vibrate. Air pressure in the chamber beyond the tympanic membrane, the middle ear, is regulated by the amount of air passing through the...

Female Reproductive Structures

The female reproductive system contains two almond-shaped ovaries that are located in the lower abdomen. The ovaries (OH-vuh-reez) are the gamete-producing organs of the female reproductive system. Eggs mature near the surface of the ovaries, which are about 3.5 cm (1.4 in.) long and 2 cm (0.8 in.) in diameter. A mature egg is released into the abdominal cavity, where it is swept by cilia into the opening of a nearby fallopian (fuh-LOH-pee-uhn) tube, or uterine tube. Smooth muscles lining the...

Gene Expression In Development

All multicellular, sexually reproducing organisms begin life as a fertilized egg, or zygote. Although every cell in the developing zygote contains all of the organism's genes, only a small number of the genes are expressed. Certain genes are turned on and off as various proteins are needed at different times during the organism's life. For example, as eukaryotes grow, cells become specialized to perform different tasks. Muscle cells specialize in movement, and liver cells specialize in making...

Circulation in the Heart

Refer to Figure 46-2 to trace the path of the blood as it circulates through the heart. Blood returning to the heart from parts of the body other than the lungs has a high concentration of carbon dioxide and a low concentration of oxygen. Q Deoxygenated (O2-poor) blood enters the right atrium. The right atrium sends deoxygenated blood into the right ventricle. The muscles of the right ventricle contract and force the blood into the pulmonary arteries. Q The pulmonary artery sends the blood to...

Golgi Apparatus

The Golgi apparatus, shown in Figure 4-16, is another system of flattened, membranous sacs. The sacs nearest the nucleus receive vesicles from the ER containing newly made proteins or lipids. Vesicles travel from one part of the Golgi apparatus to the next and transport substances as they go. The stacked membranes modify the vesicle contents as they move along. The proteins get address labels that direct them to various other parts of the cell. During this modification, the Golgi apparatus can...

Cell Mediated Immune Response

More than one type of T cell carries out the cell-mediated immune response. Interleukin-2 stimulates the further production of helper T cells. The increase in helper T cells produces an increase in interleukin-2, which allows T cells to divide even faster. Interleukin-2 is also responsible for stimulating the production of cytotoxic (siet-oh-TAHKS-ik) T cells (sometimes called killer T cells), which recognize and destroy cells that have been infected by the pathogen. Invaded cells are...

Organization Of The Nervous System

As shown in Figure 49-5, the brain and spinal cord make up the central nervous system. The brain is the control center of the nervous system, and the spinal cord carries nerve signals between the body and the brain. The brain interprets nerve signals from the body and sends response signals that pass through the spinal cord to the body. The peripheral nervous system consists of neurons that have cell bodies that are not included in the brain and spinal cord. Some peripheral neurons collect...

Antibiotic

Bacteria also cause disease by destroying body tissues. As bacteria stick to body cells, they secrete digestive enzymes that break down tissue for its nutritional value, which allows further bacterial invasion. For example, some species of the genus Streptococcus make a blood clot-dissolving enzyme that allows bacteria to spread easily from tissue to tissue. Antibiotics and Antibiotic Resistance Antibiotics affect bacteria by interfering with certain cellular activities. Penicillin...

Info

1- How do you think the membrane between segments helps the grasshopper in its movements 2- How does the function of the stiff, leathery forewings differ from that of the more delicate hindwings 3- Trace the path of food through the grasshopper's digestive tract. 4- To what system do the Malpighian tubules belong 5- Why is the circulatory system of the grasshopper described as an open circulatory system 6- Compared with invertebrates such as flatworms and earthworms, grasshoppers are highly...

Muscular Movement Of Bones

Generally, skeletal muscles are attached to one end of a bone, stretch across a joint, and are fastened to a point on another bone. Muscles are attached to the outer membrane of bone, the periosteum, either directly or by a tough fibrous cord of connective tissue called a tendon. For example, as shown in Figure 45-13, one end of the large biceps muscle in the arm is connected by tendons to the radius in the forearm, while the other end of the muscle is connected to the scapula in the shoulder....

The Logistic Model

Birth rates and death rates are not constant but vary with population size birth rates decline and death rates rise as the population grows. The logistic (loh-JIS-tik) model of population growth builds on the exponential model but accounts for the influence of limiting factors. The logistic model includes a new term, carrying capacity (symbolized by K), the number of individuals the environment can support over a long period of time. A graph of logistic growth looks like a stretched-out letter...

Other Types Of Hormones

Many other chemical messengers are now classified as hormones. These substances include neuropeptides and prostaglandins (PRAHS-tuh-GLAN-dinz). Neuropeptides are hormones secreted by the nervous system. Unlike neurotransmitters, neuropeptides tend to affect many cells near the nerve cells that release them. One group of neuropeptides, called endorphins (en-DAWR finz), regulate emotions, influence pain, and affect reproduction. Another group of neuropeptides, enkephalins (en-KEF-uh-linz),...

Ocean Zones

The ocean covers about 70 percent of Earth's surface and has an average depth of 3.7 km (2.3 mi). The deepest parts of the ocean are about 11 km (6.8 mi) deep. The water contains about 3 percent salt, mostly sodium chloride, a factor that strongly affects the biology of the organisms that live there. Another important factor affecting marine organisms is the availability of light. Most of the ocean is cold and dark. This zone, where sunlight cannot penetrate and photosynthesis cannot occur, is...

Feeding And Defense In Cnidarians

One of the distinguishing features of cnidarians is the presence of cnidocytes (NIE-duh-siets), which give the phylum its name. Cnidocytes are specialized cells used for defense and capturing prey. Figure 33-4 shows a type of cnidocyte organelle called a nematocyst (nuh-MAT-uh-sist), which has a long filament coiled up inside it. In some cnidarians, the cnidocytes are concentrated in the epidermis, especially on the tentacles. When an object brushes against the trigger on a cnidocyte, the...

Cell Division In Eukaryotes

In eukaryotic cell division, both the cytoplasm and the nucleus divide. There are two kinds of cell division in eukaryotes. The first type of cell division that you will learn about is called mitosis. Mitosis results in new cells with genetic material that is identical to the genetic material of the original cell. Mitosis occurs in organisms undergoing growth, development, repair, or asexual reproduction. Asexual reproduction is the production of offspring from one parent. The second type of...

Part C

21. ij CAUTION Do not use electrical equipment near water or with wet hands or clothing. Using a compound light microscope, focus on a prepared slide of bone by using low power, and then switch to high power. Locate a Haversian canal, the darkly stained circle in the center of a set of lamellae. Find the darkly stained osteocytes between the lamellae. 22. In your lab report, draw and label the following bone structures Haversian canal, lamella, and osteocyte. 1. What effect did water loss have...

The Skeleton

As shown in Figure 45-3, the human skeleton is composed of two parts the axial skeleton and the appendicular (AP-uhn-DIK-yuh-luhr) skeleton. The bones of the skull, ribs, spine, and sternum form the axial skeleton. The bones of the arms and legs, along with the scapula, clavicle, and pelvis, make up the appendicular skeleton.

Using A Compound Light Microscope

Proper Handling and Use of the Compound Light Microscope 1. Carry the microscope to your lab table by using both hands, one supporting the base and the other holding the arm of the microscope. Hold the microscope close to your body 2. Place the microscope on the lab table at least 5 cm (2 in.) from the edge of the table. 3. Check to see what type of light source the microscope has. If the microscope has a lamp, plug it in and make sure that the cord is out of the way If the microscope has a...

Domain Bacteria

They occur in many shapes and sizes and have distinct biochemical and genetic characteristics. Most bacteria have one of three basic shapes, as shown in Figure 23-3. Rod-shaped bacteria are called bacilli (buh-SIL-lE). Sphere-shaped bacteria are called cocci (KAHK-SIE), and spiral-shaped bacteria are called spirilla (spie-RIL-uh). When cocci occur in chains, they are called streptococci (STREP-tuh-KAHK-siE). Grapelike clusters of cocci are called...

How Can Scientists Replicate Photosynthesis in the

Life on Earth is powered by the sun's energy. The chloroplasts found in plants and some other organisms can efficiently capture and convert solar energy to sugars through a process known as photosynthesis. Now, scientists have developed an artificial photosystem that may one day allow for solar-powered food or fuel production in the lab. In nature, a photosystem contains pigments and proteins embedded in a linear sequence in the membrane of a chloroplast. This arrangment allows for effective...

Diversification Of Mammals

Dinosaurs dominated most terrestrial habitats while populations of small mammals continued to evolve. By the middle of the Cretaceous period, about 100 million years ago, three different kinds of mammals had appeared. Modern mammals belong to one of these three groups. The first group is made up of monotremes. They are oviparous, meaning that they lay eggs. The second group is made up of marsupials. They are viviparous, which means that they give birth to live young. In marsupials, the young...

Bone Function And Structure

The bones that make up the skeleton function in a variety of ways. Bones provide a rigid framework against which muscles can pull, give shape and structure to the body, and support and protect delicate internal organs. Notice, for example, that the ribs curve to form a cage that contains the heart and lungs. Similarly, bones in the skull form the cranium, a dome-shaped case that protects the brain. Bones also store minerals, such as calcium and phosphorus, which play vital roles in important...

Endoplasmic Reticulum

The endoplasmic reticulum (EN-doh-PLAZ-mik ri-TIK-yuh-luhm), abbreviated ER, is a system of membranous tubes and sacs, called cisternae (sis-TUHR-nee). The ER functions primarily as an intracellular highway, a path along which molecules move from one part of the cell to another. The amount of ER inside a cell fluctuates, depending on the cell's activity. There are two types of ER rough and smooth. The two types of ER are thought to be continuous. The rough endoplasmic reticulum is a system of...

Demographic Transition

Human populations have undergone rapid growth, yet in some developed countries, populations have stopped growing. The demographic transition model shows how these population changes happen. The theory behind the model is that industrial development causes economic and social progress that then affects population growth rates. Figure 19-13 compares general trends in birth rates, death rates, and population sizes during four stages. In the first stage of the model, the birth rate and the death...

Osmosis

A solution is composed of a solute dissolved in a solvent. In the sugar water described in Figure 5-1, the solute was sugar and the solvent was water, and the solute molecules diffused through the solvent. It is also possible for solvent molecules to diffuse. In the case of cells, the solutes are organic and inorganic compounds, and the solvent is water. The process by which water molecules diffuse across a cell membrane from an area of higher concentration to an area of lower concentration is...

Feeding And Digestion

For most mammals, the breakdown of food begins with chewing. Other vertebrates simply swallow their food whole or in large pieces. Chewing speeds up digestion by breaking food into small pieces that provide a large surface area for attack by enzymes. Variations in the size and shape of teeth among different mammalian species reflect differences in diet. Chisellike incisors cut. Pointed canines grip, puncture, and tear. Premolars shear, shred, cut, or grind. Molars grind, crush, or cut. For...

Parts Of A Flower

Recall that early land plants lacked leaves and roots and consisted of only stems. Leaves evolved from branches of stems. Botanists consider flowers to be highly specialized branches and the parts of a flower to be specialized leaves. These specialized leaves form on the swollen tip of a floral branch or receptacle. Flower parts are usually found in four concentric whorls, or rings, as shown in Figure 30-5. Sepals (SEE-puhlz) make up the outer whorl. They protect the other parts of a developing...

Circulatory System

The circulatory system of a reptile, like those of all terrestrial vertebrates, is composed of two loops. The pulmonary loop carries deoxygenated blood from the heart to the lungs and returns oxygenated blood to the heart. The systemic loop transports oxygenated blood to the tissues of the body, where oxygen and nutrients are unloaded and where carbon dioxide and wastes are picked up, and returns deoxygenated blood to the heart. In lizards, snakes, tuataras, and turtles, the heart has two atria...

Acids And Bases

One of the most important aspects of a living system is the degree of its acidity or alkalinity. What do we mean when we use the terms acid and base As water molecules move about, they bump into one another. Some of these collisions are strong enough to result in a chemical change one water molecule loses a proton (a hydrogen nucleus), and the other gains this proton. This reaction really occurs in two steps. First, one molecule of water pulls apart another water molecule, or dissociates, into...

Freeways May Provide An Effect Of Geographical Isolation

Use each of the following terms in a separate sentence bell curve and gene flow. 2. For each pair of terms, explain how the meanings of the terms differ. a. allele frequency and phenotype frequency b. stabilizing selection and disruptive selection d. geographic isolation and reproductive isolation e. allopatric speciation and sympatric speciation f. punctuated equilibrium and gradualism 3. Use the following terms in the same sentence nonrandom mating, assortative mating, and sexual selection....

Treating And Preventing Diabetes

Proteins play many important roles in living organisms. The hormone insulin is a protein that stimulates cells to take up glucose. More than 18 million Americans have diabetes, an inability of the body to make or respond to insulin. When the body cannot make or respond to insulin, the body's cells must switch to burning mainly fat as their fuel. The resulting high levels of fat in the blood can cause cardiovascular disease. In addition, the glucose that accumulates in the blood causes other...

Genetic Traits And Disorders

Many characters, such as height, weight, hair color, and skin color, are polygenic. Often, the environment strongly influences polygenic characters. Genes controlling human traits show many patterns of inheritance. Some of these genes cause genetic disorders. Genetic disorders are diseases or disabling conditions that have a genetic basis. Single genes having two or more alleles can determine traits, such as blood type or cystic fibrosis. Geneticists have learned, however, that most human...

Learned Behavior

Some aspects of behavior are influenced by genes, but to what degree can behaviors be modified by experience Learned behaviors are actions that change with experience. Learning is the modification of a behavior based on experience. Learning can influence the expression of behaviors that are innate and also behaviors that are not innate. The study of learned behavior is central to much of ethology, and learning types can vary from simple to complex. The simplest type of learning, habituation...

Plantlike Protists

Plantlike protists are classified into seven phyla based on type of pigments, form of food storage, and cell-wall composition. The characteristics of the seven phyla are summarized in Table 25-2. The phylum Chlorophyta (klaw-RAHF-uh-tuh) contains more than 17,000 identified species of protists called green algae. Green algae have an amazing number of body forms, ranging from single cells and colonies to filamentous and multicellular forms. Green algae share several characteristics with plants....

Treating Genetic Disease

Physicians can treat genetic diseases in several ways. For many diseases they can treat just the symptoms. For example, an individual with the genetic disease phenylketonuria (PKU) lacks an enzyme that converts the amino acid phenylalanine into the amino acid tyrosine. Phenylalanine builds up in the body and causes severe mental retardation. Physicians prescribe strict food regimens for phenylketonuria (PKU) patients to eliminate the amino acid phenylalanine from their diets. PKU can be...

Fungi In Industry

Fungi produce many products used in nonfood industries. Several fungal species are used in the production of important medicines. For example, species of the genus Penicillium produce the antibiotic penicillin, and species of the genus Cephalosporium produce cephalosporin antibiotics. Species of the genus Rhizopus cause chemical transformations of specific chemicals to make cortisone, an anti-inflammatory drug used to treat skin rashes and reduce joint swelling. The yeast Saccharomyces...

Darwins Ideas

At about the same time in the mid-1800s, both Charles Darwin and the English naturalist Alfred Russel Wallace (1823-1913) formed a new theory to explain how evolution may take place. Both Darwin and Wallace had been on sea voyages around the world Darwin's voyage is shown in Figure 15-3. In 1858, the ideas of Darwin and Wallace were presented to a prestigious group of scientists in London. The following year, Darwin published a book entitled On the Origin of Species by Means of Natural...

Characteristics Of Mollusks

Squid Physiology

The phylum Mollusca is a diverse group of more than 112,000 species. Among animals, only the phylum Arthropoda has more species. Some mollusks are sedentary filter feeders, while others are fast-moving predators with complex nervous systems. Mollusks are among several phyla of animals known as coelomates. Coelomates are so named because they have a true coelom, a hollow, fluid-filled cavity that is completely surrounded by mesoderm. Coelomates differ from pseudocoelomates, such as roundworms,...

Case Study Caribbean Anole Lizards

Anolis Pulchellus

Often, when scientists compare groups of species, the scientists find patterns that are best explained as evolution in progress. An example is the comparison of anole lizard species (genus Anolis) on the Caribbean islands of Cuba, Hispaniola, Jamaica, and Puerto Rico. Among these lizards, each species' body type correlates with the habitat in which the species lives, as shown in Figure 15-11. For example, anole species that live mainly on tree trunks have stocky bodies and long legs. In...

Section 3

List the characteristics of arachnids, as represented by a spider. Explain the adaptations that spiders have for a predatory life on land. Identify the unique characteristics of scorpions, mites, and ticks. Compare the characteristics of millipedes and centipedes. The major internal organs of a female spider are shown in this cutaway side view. The inset shows a closer view of a book lung, one of the spider's adaptations to life on land. from the Latin spiraculum, meaning air hole The black...

Metabolism

Urinary System Birds

Birds are endothermic that is, they generate heat to warm the body internally. Rapid breathing and digestion of large quantities of food support the high metabolic rate necessary to generate this heat. Birds, unlike reptiles, cannot go for long periods without eating. To help conserve body heat, birds may fluff out their feathers. Aquatic birds have a thin layer of fat that provides additional insulation. A bird's digestive and excretory systems are adapted for the rapid processing of food and...

Ancestral Colonial Protist

The palm spider, Nephila sp., is an arthropod, with a segmented body and body parts specialized for trapping, killing, and eating its prey. The palm spider, Nephila sp., is an arthropod, with a segmented body and body parts specialized for trapping, killing, and eating its prey. www.scilinks.org Topic Vertebrates Keyword HM61602 www.scilinks.org Topic Vertebrates Keyword HM61602 Invertebrate body plans range from the absence of body symmetry and true tissues, as is found in sponges, to...

Tobacco

Tobacco products are legal for people age 18 and older. Nicotine is the major drug found in tobacco, shown in Figure 49-17. Nicotine is a highly addictive stimulant. When a person chews tobacco or inhales its smoke, nicotine is absorbed into the bloodstream through the mouth and lungs. It is then quickly transported throughout the body and, in pregnant women, to the fetus. Nicotine mimics the action of a neurotransmitter called acetylcholine (AS-i-TlL-KOH-leen). Acetylcholine plays a role in...

Early Onset Of Puberty In Girls

Until a few decades ago, girls began puberty at about age 11 and completed puberty by about age 13. Now, it is more common to see puberty in girls beginning at about 9 and 10 years of age and sometimes as early as 6 or 7 years of age. Researchers are investigating why puberty starts earlier in girls than it used to and what type of implications this may have for a person's health. What is Causing the Early Onset of Puberty Genetics is one of several factors that influence the onset of puberty...

Nutrition And Metabolism

Prokaryotes have two chief nutritional needs a source of carbon to build the organic molecules of their cells and a source of energy. They have many ways of getting both carbon and energy from the environment. Organisms that get their carbon from other organisms are called heterotrophs. Autotrophs are organisms that get their carbon directly from the inorganic molecule carbon dioxide, CO2. Organisms that get energy from light are called phototrophs. Chemotrophs get energy from chemicals taken...

The Crayfish

The crayfish is a freshwater crustacean that is well studied because of its size and abundance. Crayfish are structurally similar to lobsters, which are marine crustaceans. Crayfish, lobsters, crabs, and shrimp are decapods (DEK-uh-PAHDZ), or members of the order Decapoda. Decapoda means 10 feet, a name used because these crustaceans have five pairs of legs that are used for locomotion. The crayfish's external structure is shown in Figure 36-7. The body is divided into two major sections the...

Treating Bacterial Diseases

Most pharmacies today carry many antibiotics for treating bacterial diseases, yet until World War II, no such medicines existed. Not until the 19th century was it discovered that bacteria could cause disease. Much of modern medicine rests on the pioneering work of the researchers discussed here. In 1677, Dutch tradesman Anton van Leeuwenhoek first observed bacteria. His hand-held microscopes magnified objects much better than other microscopes of his day did. In the sticky plaque of his own...

The Concept Of Species

You have learned that existing species are essentially changed versions of older species. The process of species formation, speciation (SPEE-shee-AY-shun), results in closely related species. Some are very similar to their shared ancestral species, whereas other descendant species become quite different over time. For many years, scientists used the internal and external structure and appearance of an organism its morphology (mawr-FAHL-uh-jee) as the chief criterion for classifying it as a...

Bacteria In Industry

Bacteria are used to make and process many common foods and important chemicals. By fermenting the lactose in milk, bacteria make sour-milk products such as buttermilk, sour cream, and yogurt. Bacteria are also used to make cheeses such as mozzarella, ricotta, cheddar, and Roquefort. Fermented foods, such as sauerkraut, pickles, kimchi, coffee, and soy sauce, are products of bacterial fermentation. Bacteria are also grown in huge fermenters to make certain chemicals, such as acetone, acetic...

Phylum Nematoda

The phylum Nematoda is made up of roundworms, worms with long, slender bodies that taper at both ends. Roundworms are among several phyla of animals known as pseudocoelomates. Pseudocoelomates are so named because they have a pseudo-coelom, which is a hollow, fluid-filled cavity that is lined by meso-derm on the outside and endoderm on the inside. Roundworms range in length from less than 1 mm to 120 cm (4 ft). In contrast to cnidarians, ctenophores, and flatworms, which have a gastrovascular...

The Gene Pool

Population geneticists use the term gene pool to describe the total genetic information available in a population. It is easy to imagine genes for the next generation as existing in an imaginary pool. If you could inventory this pool and know all of the alleles that are present, then you could apply a simple set of rules based on probability theory to predict expected genotypes and their frequencies for the next generation. Suppose, for example, that there are two alleles of a hypothetical...

Overview Of Photosynthesis

Figure 6-2 shows how autotrophs use photosynthesis to produce organic compounds from carbon dioxide (CO2) and water. The oxygen (O2) and some of the organic compounds produced are then used by cells in a process called cellular respiration. During cellular respiration, CO2 and water are produced. Thus, the products of photosynthesis are reactants in cellular respiration. Conversely, the products of cellular respiration are reactants in photosynthesis. Photosynthesis can be divided into two...

Capturing Light Energy

The first stage of photosynthesis includes the light reactions, so named because they require light to happen. The light reactions begin with the absorption of light in chloroplasts, organelles found in the cells of plants and algae. Most chloroplasts are similar in structure. As shown in Figure 6-3, each chloroplast is surrounded by a pair of membranes. Inside the inner membrane is another system of membranes called thylakoids (THIE-luh-koydz) that are arranged as flattened sacs. The...

Communication Between Neurons

A neuron can communicate with another cell across the synaptic cleft only after an action potential reaches the axon terminal. Vesicles that contain neurotransmitters are stored in the axon terminal. When an action potential reaches the axon terminal of the presynaptic neuron, the vesicles fuse with the presynaptic membrane. This fusion releases neurotransmitters into the synaptic cleft. The neurotrans-mitters quickly diffuse across the synaptic cleft and bind to receptor proteins embedded in...

Khv

Abdomen in arthropods, the posterior tagma in vertebrates, the region that comprises the posterior part of the coelom and the viscera the internal organs other than the heart, lungs, thymus (728) abdominal cavity the hollow part of the body that is below the diaphragm and above the pelvis contains the organs of digestion, excretion, and reproduction (910) abiotic factor an environmental factor that is not associated with the activities of living organisms (363) abscisic acid a hormone in plants...

Dna Repair And Skin Cancer

Sometimes, the errors that occur during DNA replication are not fixed by DNA repair enzymes. These unrepaired errors can lead to mutations. Cancer can occur if the mutations happen within genes that control cell growth and cell division. Scientists hope that by studying DNA replication and DNA repair, they can develop treatments or even cure various types of cancers. Ultraviolet light, the most energetic part of sunlight, is the Ultraviolet light, the most energetic part of sunlight, is the It...

Diversity Of Crustaceans

Marine Crustacean With Pairs Limbs

Crustaceans exist in a range of sizes, but most are small. For example, copepods (KOH-puh-PAHDZ), as shown in Figure 36-5a, are no larger than the comma in this sentence. At the other end of the size spectrum is the Japanese spider crab, shown in Figure 36-5b. With a leg span of 4 m (13 ft), this crab is the largest living arthropod. (b) Japanese spider crab, Macrocheira kaempferi Copepods are extremely abundant in marine environments and may be the most abundant animals in the world. Copepods...

First Organic Compounds

All of the elements found in organic compounds are thought to have existed on Earth and in the rest of the solar system when the Earth formed. But how and where were these elements assembled into organic compounds An important hypothesis to solve this puzzle was proposed in the 1920s by two scientists Soviet Alexander I. Oparin (1894-1980) and American John B. S. Haldane (1892-1964). They thought that the early atmosphere contained ammonia, NH3 hydrogen gas, H2 water vapor, H2O and compounds...

Class Oligochaeta

Parapodium Virus

Annelids of the class Oligochaeta generally live in the soil or in fresh water and have no parapodia. Oligochaeta means few bristles, and as the name suggests, these annelids have a few setae on each segment. The most familiar member of the class Oligochaeta is the earthworm. As you read about the earthworm, look for adaptations that enable this animal to lead a burrowing life. Identify the structures that provide the basis for dividing annelids into three classes. List the advantages of body...

Classification Of Cnidarians

Jellyfish Critical Thinking

Scientists recognize four classes of cnidarians Hydrozoa, Cubozoa, Scyphozoa, and Anthozoa. The members of these classes are known as hydrozoans, cubozoans, scyphozoans, and antho-zoans, respectively. Some species of hydrozoans live only as polyps, some live only as medusae, some alternate between these two forms, and some live as mixed colonies of polyps and medusae. Cubozoans and scyphozoans spend most of their lives as medusae, while anthozoans live only as polyps. The class Hydrozoa...

Six Kingdoms

The six-kingdom system of classification can be aligned with the newer system of three domains. However, biologists have proposed adding, subdividing, or replacing some kingdoms. Biologists have also proposed other levels of taxa. The system of three domains generally aligns with the more traditional system of six kingdoms, as represented in Figure 17-9 and summarized in Table 17-3. In the six-kingdom system, the first kingdom aligns with the domain Bacteria, the second kingdom aligns with the...

Types Of Roots

Types Roots

When a seed sprouts, it produces a primary root. If this first root becomes the largest root, it is called a taproot, as illustrated in Figure 29-3a. Many plants, like carrots and certain trees, have taproots. Contrary to what you might think, even taproots rarely penetrate the ground more than a meter or two. A few species, such as cottonwoods, do have some roots that grow 50 m (164 ft) deep to tap into underground water supplies. In some plants, the primary root does not become large....

I900 I 920 I940 I960 I980 2000

What was the relationship between number of cigarettes smoked and incidence of lung cancer F. There was no relationship between cigarette smoking and lung cancer. G. As the number of cigarettes smoked decreased, the incidence of lung cancer increased. H. As the number of cigarettes smoked increased, the incidence of lung cancer increased. J. As the number of cigarettes smoked increased, the incidence of lung cancer decreased. DIRECTIONS Complete the following analogy. 5. skin carcinoma...

Human Viral Diseases

Viruses cause many diseases in humans, such as flu, chickenpox, measles, polio, and viral hepatitis. Viral infections can affect various human organs, including the brain, liver, heart, lungs, and skin. Chickenpox and shingles are caused by the same varicella-zoster herpesvirus. The virus multiplies in the lungs and travels to blood vessels in the skin. The symptoms of chickenpox include fever and skin rash. The virus is spread through direct contact with the skin rash and through the air....

Review

Distinguish between type 1 and type 2 diabetes. 3. Critical Thinking A friend asks, Why should I worry By the time I'm old, they'll have diabetes cured anyway. What is your opinion Defend your answer. www.scilinks.org Topic Diabetes Keyword HM60400 www.scilinks.org Topic Diabetes Keyword HM60400

Harvesting Chemical Energy

Cellular respiration is the complex process in which cells make adenosine triphosphate (ATP) by breaking down organic compounds. Recall that autotrophs, such as plants, use photosynthesis to convert light energy from the sun into chemical energy, which is stored in organic compounds. Both autotrophs and het-erotrophs undergo cellular respiration to break these organic compounds into simpler molecules and thus release energy. Some of the energy is used to make ATP. The energy in ATP is then used...

Thyroid Gland

The two lobes of the thyroid (THIE-ROYD) gland are located near the lower part of the larynx, as shown in Figure 50-5. The thyroid gland produces and secretes the hormones thyroxine (thie-RAHKS-een) and triiodothyronine (TRIE-ie-oh-DOH-THIE-roh-NEEN). Both of these hormones are derived from the same amino acid and are synthesized with iodine atoms. Thyroid-stimulating hormone (TSH) regulates the release of the thyroid hormones. Release of TSH from the anterior pituitary is regulated primarily...

Subphylum Myriapoda

The subphylum Myriapoda (MIR-ee-AHP-uh-duh), includes the class Diplopoda (duh-PLAH-puh-duh), which consists of millipedes, and the class Chilopoda (KIE-LAHP-uh-duh), which consists of centipedes. Myriapoda means many feet, and is so named because myriapods have many body segments, most of which have one or two pairs of legs each. Unlike crustaceans, myriapods have one pair of unbranched antennae. They are terrestrial but lack a waxy exoskeleton. They avoid drying out by living in damp areas....

Lactose Absent

Absence Lactose

In the lac operon of E. coli, three structural genes code for the enzymes needed to utilize lactose.When lactose is absent, a repressor protein attaches to the operator. The presence of the repressor protein on the operator blocks the advancement of RNA polymerase. www.scilinks.org Topic Gene Expression Keyword HM60642 www.scilinks.org Topic Gene Expression Keyword HM60642 Lactose is a disaccharide that is composed of the two monosaccharides glucose and galactose. When E. coli bacteria are in...

Stages Of Mitosis

Mitosis is the division of the nucleus, which occurs during cell division. Mitosis is a continuous process that allows for the organized distribution of a cell's copied DNA to offspring cells. The process of mitosis is usually divided into four phases for ease of understanding prophase, metaphase, anaphase, and telophase. Prophase is the first phase of mitosis. Prophase, shown in step Q of Figure 8-6, begins with the shortening and tight coiling of DNA into rod-shaped chromosomes that can be...

Phylum Ciliophora

The nearly 8,000 species that make up the phylum Ciliophora (siL-ee-AHF-uh-ruh) share one key feature they have cilia. Cilia are short, hairlike cytoplasmic projections that line the cell membrane. Cilia make it possible for these protists to move. Members of the genus Paramecium, shown in Figure 25-5, are among the most thoroughly studied ciliates. Paramecia are found in ponds and slow-moving streams that contain plants and decaying organic matter. A paramecium has cilia arranged in rows...

Modern Amphibians

Order Caudata Eggs Images

Modern amphibians are a very diverse group, but they do share several key characteristics Most change from an aquatic larval stage to a terrestrial adult form. This transformation is called metamorphosis. Most have moist, thin skin with no scales. Feet, if present, lack claws and often are webbed. Most use gills, lungs, and skin in respiration. Eggs lack multicellular membranes or shells. They are usually laid in water or in moist places and are usually fertilized externally. Anurans (frogs and...