Biology PDF

Biology Nucleic Acids - are carriers of hereditary area of science dealing with living things. It information in living organisms. What an includes biological concepts and process organism looks like, and what it can do, are...

Biology Nucleic Acids - are carriers of hereditary area of science dealing with living things. It information in living organisms. What an includes biological concepts and process organism looks like, and what it can do, are controlled by nucleic acids. skills, technology and attitudes and values for addressing the needs and problems of Vitamins - are substances necessary in society. In recent years, the development of very small amount for body growth and techniques in genetic engineering and activity. They are also needed to prevent increased understanding of the molecular certain diseases. Vitamins are organic basis of cellular processes have led to the substances essential to life but not required emergence of a new and exciting field of as energy sources. The sources of most Vitamins are plants and bacteria. scientific research called biotechnology. 1. Introduction: INORGANIC ORGANIC COMPOUNDS-characterized by the COMPOUNDS-characterized by the absence of carbon. presence of carbon. Carbohydrates - are made up of carbon, Water - is the most abundant inorganic hydrogen, and oxygen (e.g., sugar, starches, compound. About 65% to 95% of the and cellulose) atoms. substances of every living thing is water. It is the medium of transport for food, Cellulose - gives strength and protection to minerals and other substances in living system. plant cells. Carbon dioxide - supplies the carbon Lipids – are macromolecules such as fats, found in substances made by living things. - oils and waxes.hydrogen, and oxygen. The are chemical elements or compounds building blocks used to form fats are fatty occurring naturally. They may come from acids and glycerol. Some excess food in the the soil maybe dissolved in water, or maybe body is stored as fats. Lipids that are liquid found as salt in seawater. Minerals are at room temperature are known as oils. absorbed by plant roots in the form of ions. Waxes serve as protective body covering to organisms. They make plant and animal 2. LIFE FUNCTIONS tissues water-resistant. Proteins - are made up of repeating units Nutrition- is the process of ingesting and of amino acids. They are a component of the absorbing food to provide the energy for life, muscles and all other tissues. In the form of promote growth, and repair or replace enzymes, they control the rate of chemical damaged tissues. reactions inside the cell. Without the enzymes, such chemical processes hardly occur. Enzymes - are proteins that act as catalysts (substances that can increase or speed up chemical reaction). Enzymes are specific in their actions. They are not used up in the reaction. Transport- involves movement of Its main purpose is for the perpetuation of nutrients water, ions, and other materials species. It is classified into two types, into and out of the various cells and tissues namely: of organisms. This process includes absorption of small molecules across cell 1. Asexual - is the reproduction without membranes and secretion of biochemicals the use of gametes or sex cells. One parent such as enzymes, mucous, and hormones. In organism can reproduce by itself. many species, the circulatory system plays an important role in transport. a. Fission - is the splitting of the body of an organism into two identical parts. (e.g., Metabolism -includes the process by Paramecia and planaria) which nutrients and simple molecules are used to form more complex molecules for b. Budding - is the growing of bud out of growth, repair, and reproduction the parent cells of bodies which when (anabolism). Metabolism also includes the detached can grow into another organism process of breaking down complex that resembles the appearance of parent molecules to release energy from chemical (e.g., sponges, and yeast) bonds (catabolism and to provide small molecules such as simple sugars and amino c. Sporulation - is the spore formation as in acids as budding blocks for more complex fern plant and mushrooms. molecules (anabolism). 2. Sexual - requires the union of male and An internal balance in all aspects of female gametes called "fertilization". Male metabolism and biological function is gametes are called sperm cells and female called homeostasis. gametes are called egg cells. Fertilization is classified into two types, namely: Digestion -is a special form of catabolism that breaks food down into smaller a. External Fertilization - the union of molecules and releases energy. sperm cells and egg cells happen outside the body of the female organisms. (e.g., Absorption- allows small molecules to seashells,starfishes, frogs, fishes) pass through cell membranes throughout the body tissues.This allows for a gas b. Internal Fertilization - the union of exchange and in some species such as plants sperm cells and egg cells happen inside the and fungi nutrients are obtained by body of a female organism (e.g., higher absorption from soil and water. forms of animals and human) The behavior of living things is a 3. Cells response to stimuli in the environment. These stimuli may include - are the smallest structures capable of basic things such as light, chemical signals, noise, life processes, such as taking in nutrients, or a change in the seasons. expelling waste,and reproducing. All living things are composed of cells. Some Excretion-is the elimination of waste microscopic organisms, such as bacteria and products. protozoa, are unicellular, meaning they consist of a single cell. Plants, animals, and Reproduction- is the process by which an fungi are multicellular; that is, they are organism produces offspring either sexually composed of a great many cells working in or asexually. concert. PROKARYOTIC CELL EUKARYOTIC ANIMAL CELLS - found only in bacteria and archaebacteria, - are typically about ten times larger than all the components, including the DNA, prokaryotic cells. In animal cells, the plasma mingle freely in the cell’s interior, a single membrane, rather than a cell wall, forms the compartment. cell’s outer boundary. With a design similar to the plasma membrane of prokaryotic - are among the tiniest of all cells, ranging in cells, it separates the cell from its size from 0.0001 to 0.003 mm (0.000004 surroundings and regulates the traffic to 0.0001 in) in diameter. across the membrane. - can be rod like, spherical, or spiral in Nucleus shape, are surrounded by a protective cell wall. is the largest organelle in an animal cell. It contains numerous strands of DNA. - live in a watery environment, whether it is soil moisture, a pond, or the fluid Endoplasmic Reticulum is an elongated surrounding cells in the human body. Tiny membranous sac attached to the nuclear pores in the cell wall enable water and the membrane. Endoplasmic reticulum takes substances dissolved in it, such as oxygen, two forms: rough and smooth. Rough to flow into the cell; these pores also allow endoplasmic reticulum (RER) is so called wastes to flow out. because it appears bumpy under a microscope. It functions on synthesis of Plasma Membrane is a thin membrane membrane proteins, secretory proteins and pushed up against the inner surface of the hydrolytic enzymes and also formation of prokaryotic cell wall. The plasma transport vesicles. Smooth endoplasmic membrane, composed of two layers of reticulum functions on lipid synthesis, flexible lipid molecules and interspersed carbohydrate metabolism in liver cells, with durable proteins, is both supple and detoxification in liver cells and calcium ion strong. the plasma membrane is selectively storage. permeable, meaning it allows only certain substances to pass through. Thus, the Ribosomes in eukaryotic cells have the plasma membrane actively separates the same function as those in prokaryotic cell’s contents from its surrounding fluids. cells—protein synthesis—but they differ slightly in structure. Eukaryote ribosomes Cytoplasm is the semifluid that fills the bound to the endoplasmic reticulum help cell enclosed in the plasma membrane. a assemble proteins that typically are rich storehouse that includes enzymes and exported from the cell. dissolved nutrients, such as sugars and amino acids. Smooth Endoplasmic Reticulum (SER), lacks ribosomes and has an even Ribosomes, tiny bead-like structures. surface. Within the winding channels of the These are the cell’s protein factories. smooth endoplasmic reticulum are the Following the instructions encoded in the enzymes needed for the construction of DNA, ribosomes churn out proteins by the molecules such as carbohydrates and lipids. hundreds every minute, providing needed The smooth endoplasmic reticulum is enzymes, the replacements for worn-out prominent in liver cells, where it also serves transport proteins, or other proteins to detoxify substances such as alcohol, required by the cell. drugs, and other poisons. Golgi apparatus, an organelle that 4. Life Classification of resembles a stack of deflated balloons. It is Organisms packed with enzymes that complete the processing of proteins. Lysosomes are small, often spherical Levels of Classification: organelles that function as the cell’s recycling center and garbage Kingdom -Phylum-Class-Order disposal.Powerful digestive enzymes -Family-Genus -Species concentrated in the lysosome break down worn-out organelles and ship their building Family - group of genera with related blocks to the cytoplasm where they are used characteristics. The family is below the to construct new organelles. order and above the genus in biological groupings. The names of families in modern Mitochondria are the powerhouses of the classification are usually derived from a cell. genus of the family, called the type genus. The family names of animals always end in Cytoskeleton, a dynamic network of idae, as in Equidae, the horse family;those protein tubes, filaments, and fibers, of plants almost always end in aceae, as in crisscrosses the cytoplasm, anchoring the Dipsacaceae, the teasel family. organelles in place and providing shape and structure to the cell. Genus - category of classification of living things; specifically, a group of species Chloroplasts, like mitochondria, possess a closely related in structure and evolutionary circular chromosome and prokaryote-like origin. The position of a genus, in ribosomes, which manufacture the proteins classification of the kingdoms of living that the chloroplasts typically need. forms, is below family or subfamily, and above species. Central vacuole of a mature plant cell typically takes up most of the room in the Species - is a group of closely related cell. The vacuole, a membranous bag, organisms that are able to interbreed and crowds the cytoplasm and organelles to the produce fertile offspring. edges of the cell. The central vacuole stores water, salts, sugars, proteins, and other THE 5 KINGDOMS nutrients. The Kingdom Prokarya or Bacteria are Cell wall surrounds and protects the distinguished from the life forms in all other plasma membrane. kingdoms in that they do not have a membrane bound nucleus containing the genetic material of the cell. They are called"prokaryotes". The genetic material is ANIMAL CELLS VS PLANT CELLS simply found in strands ("plasmids") within the cell's cytoplasm. Note that what was Plant cells contain cell walls, vacuoles, and previously called blue green algae are now chloroplasts that animal cells don’t. On the classified as cyanobacteria because they are other hand, animal cells have centrioles and prokaryotes. Since they are so different from lysosomes that plant cells don’t. all other life, under the five kingdom system, Bacteria also comprise the Superkingdom Prokarya. The Kingdom Animalia is comprised of i. monocotyledons multi-celled organisms which develop from an embryo resulting from the fertilization of ii. Dicotyledons an egg by a much smaller sperm. DERMAL SYSTEM The Kingdom Plantae is composed of multi-celled organisms that grow from The dermal system consists of the embryos that are usually the result of sexual epidermis, or outermost layer, of the plants fusion of a male and female cell. Again there body. It forms the skin are exceptions although somewhere in every plant's past, there were sexual forebears. of the plants, covering the leaves, flowers, roots, fruits, and seeds. Epidermal cells vary The Kingdom Fungi is comprised of greatly in function and structure. non-motile cells that have cell walls made of chitin (the same hard stuff that the outer VASCULAR SYSTEM bodies of insects are made of) and not cellulose. Therefore, some argue that fungi The vascular tissue system consists of two are more closely related to animals than kinds of conducting tissues: the xylem, plants. Fungi develop from spores without responsible for conduction of water and any embryonic stage. They digest other dissolved mineral nutrients, and the living things outside their bodies by phloem, responsible for conduction of food. releasing enzymes and then absorbing the The xylem also stores food and helps product. support the plants. Kingdom Protista is the catch-all Xylem kingdom for everything that does not fit into the other four. It is comprised of many The xylem consists of two types of microscope organisms that are of great conducting cells: tracheids and vessels. interest to this group (as well as some Elongated cells, with tapered ends and macroscopic organisms).These include secondary walls, both types lack cytoplasm protozoa (or protista under the more and are dead at maturity. The walls have modern name) and algae but also such pits—areas in which secondary thickening diverse organisms as slime molds and slime does not occur—through which water moves nets. from cell to cell. 5. Life in Organisms: Plants Phloem Classification The phloem, or food-conducting tissue, consists of cells that are living at maturity. Non- flowering or non seed forming The principal cells of phloem, the sieve plants – produces spores for propagation elements, are so called because of the clusters of pores in their walls through Flowering or seed plants which the protoplasts of adjoining cells are connected. a. Gymnosperms – seeds are expose or naked, meaning they are not enclosed within fruits. They do not produce fruits, instead they form cones. b. Angiosperms – sees are found within fruits. GROUND SYSTEM LEAF The ground, or fundamental, tissue systems The primary photosynthetic organ of most of plants consist of three types of tissue. plants. Leaves are usually flattened blades The first, called parenchyma, is found that consist,internally, mostly of throughout the plants and is living parenchyma tissue called the mesophyll, and capable of cell division at which is made up of loosely arranged cells maturity. with spaces between them.The leaf blade is connected to the stem through a narrowed Collenchyma, the second type of portion called the petiole, or stalk, which ground tissue, is also living at maturity consists mostly of vascular tissue. and is made up of cells with unevenly Appendages called stipules are often present thickened primary cell walls. Collenchyma at the base of the petiole. tissue is pliable and functions as support tissue in young, growing portions of plants. 6. Life in Organisms: Animals Sclerenchyma tissue, the third type, Types of Animals consists of cells that lack protoplasts at maturity and that have thick secondary Vertebrates walls usually containing lignin. Sclerenchyma tissue is important in -One phylum of animals, the chordates, has supporting and strengthening those been more intensively studied than has any portions of plants that have finished other, because it comprises nearly all the growing. world's largest and most familiar animals as well as humans. This phylum includes ROOTS mammals, birds, reptiles, amphibians, and fish together with a collection of The function of roots is to anchor the plants lesser-known organisms, such as sea squirts substrate and to absorb water and minerals. and their relatives. The epidermis is just behind the growing tip of roots and is covered with root hairs, Invertebrates which are outgrowths of the epidermal cells. The root hairs increase the surface area of - are far more numerous and diverse and the roots and serve as the surface through include an immense variety of animals from which water and nutrients are absorbed. sponges, worms, and jellyfish to mollusks and insects. Compose the 98 percent of the STEMS animal kingdom. The only feature these diverse creatures share in common is the Are usually above ground, grow upward, lack of a backbone. and bear leaves, which are attached in a regular pattern at nodes along the stem. The portions of the stem between nodes are called internodes. Stems increase in length through the activity of an apical meristem at the stem tip. COLD-BLOODED AND Omnivore, an animal that eats both WARM-BLOODED ANIMALS animal flesh and vegetable matter. The term omnivore indicates similarities in the Cold blooded or ectoderm behavior and physiology of many unrelated animals; for example, many small birds and - an animal whose temperature is dictated mammals are omnivorous. by its surroundings. Reptiles, amphibians, and fish. 7. ANIMAL REPRODUCTION - Although they do not maintain a constant Asexual reproduction, animals produce warm temperature, some of these animals offspring without needing a partner. do manage to raise their body temperature Asexual reproduction is most common in far above that of their surroundings. They simple animals such as flatworms and do this by behavioral means, such as cnidarians. basking in direct sunshine when the surrounding air is cool. Sexual reproduction, involves two parents. The parents produce sperm and egg Warm blooded or endoderm cells (gametes), which are brought together to form a fertilized cell (zygote) with a new - an animal that keeps its body at a constant and unique combination of genes. In this warm temperature by generating internal genetic lottery, offspring inherit unique heat. combinations of characteristics that increase the likelihood that at least some - these animals generate heat through their individuals in the population can survive metabolic processes, and they retain it by changes in the environment. having insulating layers of fat, fur, or feathers. Because their bodies are always Internal fertilization takes place inside warm, they can remain active in some of the the female's body. The male typically has a coldest conditions on earth. penis or other structure that delivers sperm into the female's reproductive tract. All Plant-eaters, or herbivores, often do mammals, reptiles, and birds as well as not have to search far to find things to eat, some invertebrates, including snails, worms, and in some cases—for example and insects, use internal fertilization. wood-boring insects—they are entirely surrounded by their food. The disadvantage of a plant-based diet is that it can be difficult to digest and is often low in nutrients. Carnivores live on flesh from other animals that is often nutrient-rich and easy to digest but difficult to obtain.Finding and capturing this kind of food calls for keen senses. But even though a hunter has acute vision or a highly developed sense of smell, a large proportion of a hunter's victims manage to escape. If this happens too often, a predator quickly starves.  8. Organ Systems of the Body sometimes called the “fight or flight” system, increases alertness, stimulates MUSCULOSKELETAL SYSTEM tissue, and prepares the body for quick responses to unusual situations. In contrast, The human skeleton consists of more than the parasympathetic nervous system, 200 bones bound together by tough and sometimes called the “rest and relatively inelastic connective tissues called repose” system, conserves energy and ligaments. The different parts of the body controls sedentary activities, such as vary greatly in their degree of digestion. movement.Thus, the arm at the shoulder is freely movable, whereas the knee joint is The nervous system has two divisions: definitely limited to a hingelike action. The the somatic, which allows voluntary movements of individual vertebrae are control over skeletal muscle, and the extremely limited; the bones composing the autonomic, which is involuntary and skull are immovable. Movements of the controls cardiac and smooth muscle bones of the skeleton are effected by and glands. The autonomic nervous contractions of the skeletal muscles, to system has two divisions: the which the bones are attached by tendons. sympathetic and the parasympathetic. These muscular contractions are controlled Many, but not all, of the muscles and glands by the nervous system. that distribute nerve impulses to the larger interior organs possess a double nerve NERVOUS SYSTEM supply; in such cases the two divisions may exert opposing effects. Thus, the The nervous system is composed of the sympathetic system increases central nervous system and the peripheral heartbeat, and the parasympathetic nervous system.The central nervous system decreases heartbeat. The two system,which includes the brain and spinal nervous systems are not always cord,processes and coordinates all incoming antagonistic. sensory information and outgoing motor commands, and it is also the seat of complex Human Brain brain functions such as memory, intelligence, learning, and emotion. The human brain has three major structural components: the large The peripheral nervous system includes dome-shaped cerebrum (top), the all neural tissue outside of the central smaller somewhat spherical nervous system. It is responsible for cerebellum (lower right), and the providing sensory, or afferent, brainstem (center). information to the central nervous system and carrying motor, or Prominent in the brainstem are the efferent, commands out to the body’s medulla oblongata (the egg-shaped tissues. Voluntary motor commands, enlargement at center) and the such as moving muscles to walk or thalamus (between the medulla and talk, are controlled by the somatic the cerebrum). The cerebrum is nervous system, while involuntary responsible for intelligence and reasoning. motor commands, such as digestion The cerebellum helps to maintain and heart beat, are controlled by the balance and posture. The medulla is autonomic nervous system. The involved in maintaining involuntary autonomic nervous system is further functions such as respiration, and the divided into two systems. The sympathetic thalamus acts as a relay center for nervous system, electrical impulses traveling to and from the cerebral cortex. CIRCULATORY SYSTEM Human Lungs Human Circulatory System Air travels to the lungs through a series of tubes and airways. The two branches of the The human circulatory system is composed trachea, called bronchi, subdivide within the of the muscular heart and an intricate lobes into smaller and smaller air vessels. network of elastic blood vessels known as They terminate in alveoli, tiny air sacs arteries, veins, and capillaries. These surrounded by capillaries. When the alveoli structures work together to circulate blood inflate with inhaled air, oxygen diffuses into throughout the body, in the process the blood in the capillaries to be pumped by delivering life-preserving oxygen and the heart to the tissues of the body, and nutrients to tissue cells while also removing carbon dioxide diffuses out of the blood into waste products. the lungs, where it is exhaled. IMMUNE SYSTEM THE ENDOCRINE SYSTEM Lymphocyte Pituitary Gland Scanning electron micrograph of a normal T Called the master gland, the pituitary lymphocyte. T lymphocytes are specialized secretes hormones that control the activity white blood cells that identify and destroy of other endocrine glands and regulate invading organisms such as bacteria and various biological processes. Its secretions viruses. Some T lymphocytes directly include growth hormone (which stimulates destroy invading organisms, whereas other cellular activity in bone, cartilage, and other T lymphocytes regulate the immune system structural tissue); thyroid stimulating by directing immune responses. The body hormone (which causes the thyroid to defends itself against foreign proteins and release metabolism-regulating hormones); infectious microorganisms by means of a antidiuretic hormone (which causes the complex dual system that depends on kidney to excrete less water in the urine); recognizing a portion of the surface pattern and prolactin (which stimulates milk of the invader. The two parts of the system production and breast development in are termed cellular immunity, in which females). The pituitary gland is influenced lymphocytes are the effective agent, and both neurally and hormonally by the humoral immunity, based on the action of hypothalamus. antibody molecules. DIGESTIVE AND EXCRETORY RESPIRATORY SYSTEM SYSTEMS Respiration is carried on by the expansion Human Digestive System The human and contraction of the lungs; the process digestive system consists of a series of and the rate at which it proceeds are organs and structures that help break down controlled by a nervous center in the brain. food and absorb nutrients for use throughout the body. Food enters the digestive system through the mouth and passes through the esophagus, stomach, small intestine, large intestine, and rectum. Other organs, such as the liver, further aid in the breakdown of food, absorption of nutrients, and elimination of indigestible materials from the body. INTEGUMENTARY SYSTEM 2. Metaphase- each chromosome moves toward an imaginary line, called the Structure of the Skin equatorial plate,that divides the cell into two; the chromosomes are perpendicular to The skin consists of an outer, protective the long axes of the spindle fibers. layer (epidermis) and an inner, living layer (dermis). The top layer of the 3. Anaphase- the kinetochore that joins epidermis is composed of dead cells two sister chromatids together splits and containing keratin, the horny scleroprotein each chromatid or single stranded that also makes up hair and nails.The skin is chromosome moves toward opposite poles. an organ of double-layered tissue stretched over the surface of the body and protecting 4. Telophase- the single stranded it from drying or losing fluid, from harmful chromosomes relax into the extended state external substances, and from extremes of upon reaching the poles; the nuclear temperature. The inner layer, called the membrane and nucleolus reform in each dermis, contains sweat glands, blood pole. Cytokinesis, which divides the vessels, nerve endings (sense cytoplasm, usually occurs at the latter part receptors), and the bases of hair and of this stage. nails. The outer layer, the epidermis, is only a few cells thick; it contains Meiosis pigments, pores, and ducts, and its surface is made of dead cells that it Meiosis takes place in special cells that sheds from the body. (Hair and nails are produce what we call the sex cells. During adaptations arising from the dead cells.) meiosis, two cell divisions occur to produce The sweat glands excrete waste and cool the four daughter cells from the original parent body through evaporation of fluid droplets; cell. Each resulting cell has half the the blood vessels of the dermis supplement chromosomal DNA of the parent cell. A half temperature regulation by contracting to set of chromosomes in an organism is preserve body heat and expanding to known as the haploid number. In the first dissipate it. Separate kinds of receptors cell division of meiosis the chromosomes of convey pressure, temperature, and pain. Fat a gamete cell duplicate and join in pairs. cells in the dermis insulate the body, and oil The paired chromosomes align at the glands lubricate the epidermis. equator of the cell, and then separate and move to opposite poles in the cell. The cell 9. Cell Division and Reproduction then splits to form two daughter cells. As meiosis proceeds, the two daughter cells Mitosis undergo another cell division to form four cells, each of which bears half of the number Cell division produces two daughter cells in of chromosomes found in the other cells of each succession that are roughly identical the organism. It also ensures that copies of the parental cell before it starts to reproduction will produce a zygote that has enlarge or grow. This kind of cell division received one set of chromosomes from the constitutes what is exactly called mitosis. male parent and one set of chromosomes Mitosis is made up of four main stages: from the female parent to form a full set of chromosomes. The entire set of 1. Prophase- each chromosome gradually chromosomes in an organism is known as condenses and thickens, and becomes more the diploid number. Once formed, the visible even under an ordinary light zygote continues to divide and grow through microscope; the nuclear membrane and the process of mitosis. nucleolus gradually dissociate and spindle fibers radiating from two opposite poles are formed. Prophase 1 Telophase 2 The nuclear membrane breaks down the nuclear membrane appears The nucleolus disappear the membrane pinches completely Spindle fibers begin to form to form cell Single chromosome strands appear and double up Metaphase 1 10.Heredity Two sister chromatids pair with its - process of transmitting biological homologous sister chromatids traits from parent to offspring crossing over between the through genes, the basic units of homologous pair heredity. Heredity also refers to the spindle fibers completely forms inherited characteristics of an individual, including traits such as Anaphase 1 height, eye color, and blood type. homologues of each pair split and Some of Mendel’s Basic move to the opposite sides, the Concepts chromosomes number on each side is half the original number GENETICS is the study of how the cell membrane begins to pinch heredity works and, in particular, of genes. Telophase 1 GENE is a section of a long the nucleolus appear deoxyribonucleic acid (DNA) the nuclear membranes fro molecule, and it carries information pinching of the cell membrane is for the construction of a protein or completed so there are two new cells part of a protein. Through the diversity of proteins they code for, genes influence or determine such traits as eye color, the ability of a Prophase 2 bacterium to eat a certain sugar, or the number of peas in a pod. A virus Spindle fibers begin to form has as few as a dozen genes. A the nuclear membrane breaks simple roundworm has 5000 to 8000 genes, while a corn plant has Metaphase 2 60,000. The construction of a human requires an estimated the chromosomes align at the center 50,000 genes. spindle fibers form completely ALLELES are members of a gene Anaphase 2 pair. the chromatids of each chromosome GENOTYPE – The genetic are pulled apart and move toward composition of a cell or individual. opposite sides Genotypes can be any of the following  1. AA – homozygous chromosomes—a female. When a sperm dominant (made of two with a Y chromosome unites with an egg, dominant alleles) however, the result is a child with one X and 2. Aa – a heterozygous one Y chromosome—a male. Thus, the dominant (made of one father determines the gender of the child. dominant and one recessive allele CODOMINANCE- when the two alleles in 3. Aa – homozygous a gene pair appear together in the individual recessive (made up of two that is heterozygous for the trait. recessive alleles) Dominant-Recessive Inheritance PHENOTYPE – the expression or manifestation of the genotype (can The dominant-recessive pattern of be morphological, physiological or inheritance, a relatively simple pattern, biochemical, sexual, behavioral) involves paired alleles that influence one trait. In this pattern, one of the two alleles 1. AA- will exhibit a dominant contains information for a certain trait characteristic—the lavender color of sweet 2. Aa- will also exhibit a pea flowers, for example—while the second dominant trait allele directs the production of an alternate 3. Aa – will exhibit the characteristic—the white flower color. In recessive trait sweet peas, if these two alleles occur together, the allele for lavender flowers is LAW OF INDEPENDENT expressed, and the flowers are lavender. The SEGREGATION allele for lavender is therefore called the dominant allele. The allele for white is -states that members of a gene 9 pair) known as the recessive allele. Lavender separate independently of the separation of flowers also occur when two alleles for the other gene pairs during meiosis or lavender color are paired. Only when two gamete formation alleles for the recessive characteristic are paired do white flowers appear. This genetic LAW OF INDEPENDENT rule applies regardless of the organism or ASSORTMENT the trait. In the dominant recessive pattern, the recessive trait shows up only when two -states that different gene pairs assort to recessive alleles are paired. recombine with each other independently of the assortment of the other gene pairs during meiosis or gamete formation. Females have two X chromosomes, and males have one X and one Y chromosome. The Y chromosome is about one-third the size of the X chromosome. A sperm, the reproductive cell produced by the male, can carry either one X or one Y chromosome. An egg, the reproductive cell produced by the female, can carry only the X chromosome. When a sperm with an X chromosome unites with an egg, the result is a child with two X Polygenic Inheritance Food Web A significant number of human traits, such A set of interconnected food chains by as eye color, skin color, height, weight, and which energy and materials circulate within muscle strength are typically regulated by an ecosystem (see Ecology). The food web is more than one allele in a pattern known as divided into two broad categories: the polygenic inheritance. Several thousand grazing web, which typically begins with alleles, for example, may combine to green plants, algae, or photosynthesizing determine a person’s potential for plankton, and the detrital web, which begins pole-vaulting, and several hundred may play with organic debris. These webs are made a role in establishing a person’s normal up of individual food chains. In a grazing weight. Certain diseases may result from web, materials typically pass from plants to mutations in one or more alleles involved in plant eaters (herbivores) to flesh eaters polygenic inheritance. Researchers have (carnivores). In a detrital web, materials identified nearly a dozen mutated alleles pass from plant and animal matter to that are associated with diabetes mellitus, bacteria and fungi (decomposers), then to and a similar number are linked to asthma. detrital feeders (detritivores), and then to Heart disease may be linked to two or three their predators (carnivores). times that number. Some types of cancer may be correlated with more than 100 Ecosystem different genes. Polygenic inheritance is quite complex, and the ways in which Organisms living in a particular multiple genes interact to produce traits are environment, such as a forest or a coral reef, not fully understood. and the physical parts of the environment that affect them. A community of interacting living and nonliving things. Producers, consumers,decomposers, and abiotic matter 11. Ecology form an integrated, functioning whole driven by the Sun’s energy. The study of the relationship of plants and animals to their physical and biological Symbiosis environment. The physical environment includes light and heat or solar radiation, (Greek symbioun, “to live together”), in moisture, wind, oxygen, carbon dioxide, biology, term for the interdependence of nutrients in soil, water, and atmosphere. different species, which are sometimes The biological environment includes called symbionts. There are three main organisms of the same kind as well as other types of symbiosis, based upon the specific plants and animals. relationship between the species involved: mutualism, parasitism, and commensalism. Food Chain A succession of organisms in an ecological community that constitutes a continuation of food energy from one organism to another as each consumes a lower member and in turn is preyed upon by a higher member. PARASITISM claim and hold onto a site until they lose vigor or die. These prevent other individuals Also known as antagonistic symbiosis, one from surviving by controlling light, organism receives no benefits and is often moisture, and nutrients in their immediate injured while supplying nutrients or shelter areas. for the other organism (see Parasite). Parasites include viruses and bacteria that PREDATION cause many diseases; certain protozoans that can infect plants and animals; One of the fundamental interactions is tapeworms and flukes that infest the predation, or the consumption of one living intestinal tracks and internal organs of organism, plant or animal, by another. animals; and external parasites such as lice Predation on plants involves defoliation by and ticks. There are also parasitic plants like grazers and the consumption of seeds and mistletoe that draw their nourishment from fruits. The abundance of plant predators, or the branches of other plants. herbivores, directly influences the growth and survival of the carnivores. Thus, COMMENSALISM predator-prey interactions at one feeding level influence the predator-prey relations at Is an association between two different the next feeding level. In some kinds of nonparasitic animals, called communities, predators may so reduce commensals, that is harmless to both and in populations of prey species that a number of which one of the organism benefits. Many competing species can coexist in the same commensals are free to separate. Other area because none is abundant enough to commensals function together so control the resource. When predators are completely that they cannot separate. They reduced or removed, however, the dominant are not considered parasitic, however, species tend to crowd out other competitors, because they do not harm each thereby reducing species diversity. other.Commensalism is most common among marine invertebrates, but it often COEVOLUTION occurs among land animals—for example, in the association of ants with other insects The joint evolution of two unrelated species such as aphids and beetles. The association that have a close ecological of colon bacteria with humans and other relationship—that is, the evolution of one animals, especially plant-eating animals, is species depends in part on the evolution of also a type of commensalism. the other. Coevolution is also involved in predator-prey relations. Over time, as COMPETITION predators evolve more efficient ways of capturing or consuming prey, the prey When a shared resource is in short supply, evolves ways to escape predation. Plants organisms compete, and those that are more have acquired such defensive mechanisms successful survive.Within some plant and as thorns, spines, hard seed-coats, and animal populations, all individuals may poisonous or ill-tasting sap that deter share the resources in such a way that none would-be consumers. Some herbivores are obtains sufficient quantities to survive as able to breach these defenses and attack the adults or to reproduce. Among other plant plant. Certain insects, such as the monarch and animal populations, dominant butterfly, can incorporate poisonous individuals claim access to the scarce substances found in food plants into their resources and others are excluded. own tissues and use them as a defense Individual plants tend to against predators.