Ecosystem Disruption

The human impacts on air, climate, land, and water described above are happening at the same time. These impacts contribute to ecosystem disruption, the destruction or substantial change in the functioning of natural ecosystems. Ecosystem disruption is evident as species and sometimes entire communities disappear. Organisms generally require specific habitats in order to thrive. For example, when whooping cranes are in their winter nesting grounds in Texas, they eat blue crabs. Along their...

Basic Parts Of A Cell

Most animal cells have a cell membrane, a nucleus, and a variety of other organelles embedded in a watery substance. The surface of the cell membrane can be seen in (a). The organelles inside the cell are labeled in the diagram (b). Despite the diversity among cells, three basic features are common to all cell types. All cells have an outer boundary, an interior substance, and a control region. The cell's outer boundary, called the plasma membrane (or the cell membrane), covers a cell's surface...

A

It is a disease-causing virus. 6. How is a bacterial plasmid described after donor DNA is inserted into the bacterium's DNA DIRECTIONS Complete the following analogy. 7. Proteomics proteins genomics INTERPRETING GRAPHICS The diagram below is of two pieces of DNA that were cut with the same restriction enzyme. Use the diagram to answer the question that follows.

Two Basic Types Of Cells

Fossil evidence suggests that the earliest cells on Earth were simple cells similar to some present-day bacteria. As cells evolved, they differentiated into two major types prokaryotes and eukaryotes. Prokaryotes (proh-KAR-ee-OHTS) are organisms that lack a membrane-bound nucleus and membrane-bound organelles. Although prokaryotic cells lack a nucleus, their genetic information in the form of DNA is often concentrated in a part of the cell called the nucleoid. Figure 4-7 shows a typical...

Body Plan Of Sponges

Sponges are aquatic animals that make up the phylum Porifera (pohr-IF-uhr-uh). These simple organisms clearly represent the transition from unicellular to multicellular life. Because sponges are het-erotrophic, multicellular organisms that do not have cell walls, they are classified as animals. Sponges have no gastrula stage, exhibit less cell specialization than most other animals, and have no true tissues or organs. But sponges do have a key property of all animal cells cell recognition. A...

Conservation And Restoration Biology

As human populations have increased rapidly, so has the human impact on ecosystems. Scientific understanding of these impacts is weak, but is improving. Meanwhile, individuals, such as the students in Figure 22-9, can contribute to scientific understanding and also take responsibility for minimizing human impacts on ecosystems. In a discipline called conservation biology, scientists seek to identify, protect, and manage natural areas that still retain much biodiversity. Where humans have had...

Gto

Make a table of gestation periods for different mammals. Make three columns labeled Mammal, Gestation period, and Offspring per pregnancy. 2. Fill in your table with the following data Bat, 210 days, 1 offspring Gerbil, 19-21 days, 4-7 offspring Horse, 332-342 days, 1 offspring Monkey, 226-232 days, 1 offspring Rabbit, 31 days, 3-6 offspring Squirrel, 44 days, 3 offspring Whale, 420-430 days, 1 offspring Wolf, 63 days, 4-5 offspring Analysis Make a graph that relates gestation length and the...

Class Cestoda

Critical Thinking Cycle

About 5,000 species of tapeworms make up the class Cestoda. Tapeworms can live in the intestines of almost all vertebrates. Humans may harbor any of seven different species. Tapeworms enter their host when the host eats raw or undercooked food containing eggs or larvae. A tapeworm infection may cause digestive problems, weight loss, lack of energy, and anemia, which is a decrease in the number of red cells in the blood. Like flukes, tapeworms are surrounded by a tegument that protects them from...

Autonomic Nervous System

Also within the peripheral nervous system's motor division is the autonomic nervous system. This system controls internal body conditions by regulating smooth muscles in blood vessels and organs. The autonomic nervous system controls respiration, heartbeat, digestion, and other aspects of homeostasis. The autonomic system has two subdivisions the sympathetic division and the parasympathetic division. These subdivisions stimulate or inhibit body systems, as shown in Table 49-1. Physical or...

The Excretory Organs

The lungs, the kidneys, and the skin all function as excretory organs. The main excretory products are carbon dioxide, nitrogen wastes (urea), salts, and water. The lungs excrete carbon dioxide and water vapor in exhaled air. The kidneys excrete nitrogen wastes, salts, water, and other substances in urine. The skin excretes water, salts, small amounts of nitrogen wastes, and other substances in sweat. Although the kidneys, lungs, and skin belong to different organ systems, they all have a...

Root Structures

Root structures are adapted for several functions. Study Figure 29-5. Notice that the root tip is covered by a protective root cap, which covers the apical meristem. The root cap produces a slimy substance that functions like lubricating oil, allowing the root to move more easily through the soil as it grows. Cells that are crushed or knocked off the root cap as the root moves through the soil are replaced by new cells produced in the apical meristem, where cells are continuously dividing. Root...

Mutations

Cystic fibrosis results from a mutation. A mutation is a change in the nucleotide-base sequence of a gene or DNA molecule. Germ-cell mutations occur in an organism's gametes. Germ-cell mutations do not affect the organism itself, but they can be passed on to offspring. Somatic-cell (soh-MAT-ik SEL) mutations take place in an organism's body cells and can therefore affect the organism. For example, certain types of human skin cancer and leukemia result from somatic-cell mutations. Somatic-cell...

Body Plan Of Cnidarians

Tiny freshwater hydra, stinging jellyfish, and flowerlike coral all belong to the phylum Cnidaria. Animals in this phylum are called cnidarians. As you can see in Figure 33-3, the body of a cnidarian may be either bell-shaped or vase-shaped. The bell-shaped medusa (me-DOO-suh) is specialized for swimming. In contrast, the vase-shaped form, called a polyp (PAHL-ip), is specialized for a sessile existence. Figure 33-3 also shows that all cnidarians have bodies constructed of two cell layers an...

Gene Expression In Eukaryotes

The int in the word intron comes from the int in the word intervening. The ex in the word exon comes from the ex in the word expressed. Eukaryotes are vastly different from prokaryotes. Their genomes are much larger than those of prokaryotes. In addition, the DNA of eukaryotic cells is located in several individual chromosomes instead of in the single circular chromosome that occurs in prokary-otes. Finally, most eukaryotes are multicellular organisms made of specialized cells. Although each...

Nonfood Uses Of Plants

In addition to providing us with food, plants provide us with thousands of other essential products. It is hard to imagine how we could live without plants, given the variety of products that contain substances from plants. The ancient Greeks treated headaches with the bark of the white willow tree, which contains the chemical salicin. This use gave scientists the idea to test the chemical acetylsalicylic (uh-SEET-uhl-SAL-uh-SIL-ik) acid. The willow is in the genus Salix, hence the names...

Central Vacuole

Plant cells may contain a reservoir that stores large amounts of water. The central vacuole is a large, fluid-filled organelle that stores not only water but also enzymes, metabolic wastes, and other materials. The central vacuole, shown in Figure 4-22, forms as other smaller vacuoles fuse together. Central vacuoles can make up 90 percent of the plant cell's volume and can push all of the other organelles into a thin layer against the plasma membrane. When water is plentiful, it fills a plant's...

Telophase And Cytokinesis

O During prophase, the copied DNA coils into chromosomes. Q During metaphase, the chromosomes line up along the midline of the dividing cell. O During anaphase, the chromatids of each chromosome begin moving toward opposite poles of the cell. O During telophase, the chromosomes reach opposite poles of the cell, and a cleavage furrow is formed. Cytokinesis follows. from the Greek kinetos, meaning moving, and choros, meaning place

And Cytokinesis I

Meiosis occurs in diploid reproductive cells. Before meiosis begins, the DNA of the diploid reproductive cells is copied. Meiosis I results in two haploid cells. Meiosis II results in four haploid offspring cells. Crossing-over occurs when chromosomes that make up a tetrad exchange portions of their chromatids during synapsis. Crossing-over results in an exchange of genes and in new combinations of genes. Crossing-over occurs when chromosomes that make up a tetrad exchange portions of their...

Chapter Review

For each pair of terms, explain how the meanings of the terms differ. 2. Explain the relationships between carcinogen and mutagen. 3. Use the following terms in the same sentence gene, gene expression, regulator gene, and repressor protein. 4. Word Roots and Origins The word morphogenesis is derived from the Greek morphe, which means shape, and the Latin genus, which means birth. Using this information, explain why the term morphogenesis is a good name for the biological process that the term...

From Molecules To Celllike Structures

Sidney Fox (1912-1998) and others have done extensive research on the physical structures that may have given rise to the first cells. These cell-like structures, such as the ones shown in Figure 14-7, form spontaneously in the laboratory from solutions of simple organic chemicals. The structures include microspheres, which are spherical in shape and are composed of many protein molecules that are organized as a membrane, and coacervates (coh-AS-uhr-VAYTS), which are collections of droplets...

Nervous System In Cnidarians

Nervous responses in cnidarians are controlled by a diffuse web of interconnected nerve cells called a nerve net. In many cnidarians, like the polyp shown in Figure 33-5, the nerve net is distributed uniformly throughout the entire body. There is no brain or similar structure that controls the rest of the nerve net. But in the medusa form of some cnidarians, such as jellyfish, some of the nerve cells are clustered in rings around the edge of the bell-shaped body. The nerve net enables...

Characteristics Of Life

The world is filled with familiar objects, such as tables, rocks, plants, pets, and automobiles. Which of these objects are living or were once living What are the criteria for assigning something to the living world or the nonliving world Biologists have established that living things share seven characteristics of life. These characteristics are organization and the presence of one or more cells, response to a stimulus (plural, stimuli), homeostasis, metabolism, growth and development,...

Evolution Of Dinosaurs

Beginning about 235 million years ago, dinosaurs, a group of extinct reptiles, dominated life on land for roughly 150 million years. They evolved from thecodonts, an extinct group of crocodilelike reptiles. Dinosaurs include a wide variety of reptiles that were adapted to very different environments. One factor that affected dinosaur evolution was the movement of the continents. Early in the Mesozoic era, Pangaea started to break apart. The climates of the separate landmasses changed. Some...

Three Domains Of Life

Phylogenetic analyses of rRNA genes gave scientists new insights about the relationships between major groups and suggested a new tree of life. Three of the most important insights were as follows 1. The data are consistent with the hypothesis that all living organisms inherited their rRNA genes from an ancient organism or form of life. Scientists refer to this unknown ancestor as the last universal common ancestor. 2. At the broadest level, all living things seem to be related by ancestry to...

Extended Response

During the 1950s, a number of women were prescribed thalidomide, a drug to relieve morning sickness. These women gave birth to babies with serious limb defects. Scientists later discovered that thalidomide caused limb defects in fetuses. Part A Do you think it is safe for a woman to take thalidomide during her first and second trimesters of pregnancy Explain your answer. Part B Do you think it is safe for a woman to take thalidomide during the third trimester of her pregnancy Explain your...

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,...

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...

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...

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

Antennapedia Fruit Fly

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

Ano Ang Bullying

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

Golgi Apparatus

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...

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

Mucor Tofu

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

Meaning Figure Bird

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

Picture Internal Organs Side View

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...