Semester II Final Exam Study Guide

Asexual/Sexual Reproduction & Mitosis/MeiosisCell Division and Mitosis A. Cell division—increases the number of cells and causes many-celled organisms to grow B. Mitosis—process in which the nucleus divides to form two identical nuclei C. Results of mitosis

1. Each cell in your body, except sex cells, has the same number of 46 chromosomes. 2. Allows growth and replaces worn out or damaged cells

D. Asexual reproduction—a new organism is produced from one parent organism. 1. An organism with no nucleus divides into two identical organisms by fission. 2. Budding—a small, exact copy of the adult grows from the body of the parent. 3. In regeneration, a whole new organism grows from each piece of the parent.

Sexual Reproduction and Meiosis A. Sexual reproduction—two sex cells, usually an egg and a sperm, come together.

1. Fertilization—the joining of an egg and a sperm, generally from two different organisms of the same species a. Sperm are formed in the male reproductive organs. b. Eggs are formed in the female reproductive organs. c. A cell that forms from fertilization is a zygote.

2. Following fertilization, mitosis begins and a new organism develops. B. Division of sex cells

1. Body cells are diploid, because they have 23 pairs of similar chromosomes. 2. Sex cells are haploid, because they have 23 single chromosomes. 3. Meiosis—a process that produces haploid sex cells (Meiosis produces 4 cells)

Asexual reproduction Sexual Reproduction

Only one parent cell or organism is required Two parent cells and organisms are needed

Mitosis meiosis

Offspring are clones of parents Offspring show variation

Section 3 - DNA A. DNA—a chemical that contains information that an organism needs to grow and function. It is stored in the nucleus of every cell.

1. Watson and Crick made an accurate model of DNA in 1953. 2. The structure of DNA is similar to a twisted ladder.

a. The sides of the ladder are made up of sugar-phosphate molecules. b. The rungs of the ladder are made up of nitrogen bases.

3. Before a cell divides, its DNA duplicates itself by unwinding and separating its sides, then forming new sides. B. Genes—sections of DNA on a chromosome

1. Contain instructions for making specific proteins 2. Cells use only the genes that direct the making of proteins needed by that cell.

C. Mutations—any permanent change in the DNA sequence of a cell’s gene or chromosome 1. Can be caused by outside factors like X rays, sunlight, and some chemicals 2. A change in a gene or chromosome can change the traits of an organism

Chapter 13 Notes – HereditySection 1 - Genetics

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A. Heredity - the passing of traits from parent to offspring 1. Genes on chromosomes control the traits that show up in an organism. 2. The different forms of a trait that a gene may have are alleles. 3. During meiosis a pair of chromosomes separates and the alleles move into separate cells. 4. Each chromosome now contains one gene for each trait. 5. The study of how traits are inherited is genetics.

B. Gregor Mendel - the father of genetics 1. Mendel was the first to use mathematics of probability to explain heredity and to trace one trait for several generations. 2. Hybrid - receives different genetic information for a trait from each parent

a. Dominant allele - covers up or dominates the other trait b. Recessive allele - the trait seems to disappear

3. Probability helps you predict the chance that something will happen. 4. A Punnett square can help you predict what an offspring will look like.

a. Upper case letters stand for dominant alleles. b. Lowercase letters stand for recessive alleles.

5. Genotype - the genetic makeup of an organism a. homozygous - an organism with two alleles for one trait that are the same (written TT)b. Purebread or pure – (same as homozygous) an organism with two alleles for one trait that are the same (written TT)c. heterozygous - an organism with two alleles for one trait that are different (written Tt)d. Hybrid – (same as heterozygous) an organism with two alleles for one trait that are different (written Tt)

6. Phenotype - the way an organism looks and behaves as a result of its genotype. (example: brown hair, blue eyes, being 6’0”tall)

Section 2 - Genetics Since Mendel A. Incomplete dominance

1. Neither allele for a trait is dominant. 2. The phenotype produced is intermediate between the two homozygous parents.

B. Mutations - genes that are altered or copied incorrectly

Selective breeding (or artificial breeding) is the process of breeding the animals or plants with the characteristics you want with other animals or plants with those characteristics to produce more animals (plants) with good characteristics over many generation. This must be continued over many generations, taking offspring and breeding them with the ones you already have, and you will get many animals (plants) with the desired traits.

Selective breeding helps us make Better beef – Selecting for the best texture, appearance etc Better milk – Choosing cows which give highest yield Better chickens – Bigger eggs Better wheat – Growing disease resistant wheat Better flower – Choosing the biggest and most colorful flowers

Evolution Evolution refers a change in the gene frequency of a population. (A gradual change to a species that occurs over

time) For example, suppose that in a certain human population in 1990, 65% of the eye color genes were for blue eyes and

35% were for brown eyes. In 2000, the number of blue eye genes was 67%. This small evolutionary change may not be noticeable, but over time, small differences accumulate to produce larger differences. A number of natural phenomena can act to change gene frequencies.

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Organisms moving into or out of a population (migration) can cause gene frequencies to change. Random fluctuations can also cause changes, particularly in small populations.

Natural selection (described below) is particularly important in causing changes in gene frequencies.

Adaptation Adaptations are structures or behaviors that allow efficient use of the environment. For example, the webbed foot

of a duck enables it to swim better than a foot that is not webbed. Adaptations are due to genes, that is, they are inherited.

Natural SelectionNatural selection is one of several different mechanisms that cause evolutionary change in populations. Natural

selection operates to produce individuals that are better adapted to their environment. It is important to keep in mind as you read below that natural selection does not act on individuals; it acts on populations. Individual organisms cannot become better-adapted to their environment because they cannot change their genes.

Natural selection produces changes in the genetic composition of a population from one generation to the next. As a result, organisms become better adapted to their environment.

Traits Are HeritableThose individuals that survive better or reproduce more will pass their superior genes to the next generation.

Individuals that do not survive well or that reproduce less as a result of "poorer genes" will not pass those genes to the next generation in high numbers. As a result, the population will change from one generation to the next. The frequency of individuals with better genes will increase. This process is called natural selection.

Natural Selection Produces Evolutionary ChangeIf the conditions discussed above are met, the genetic composition of the population will change from one

generation to the next. This process is called natural selection.The word "evolution" refers to a change in the genetic composition of a population. Natural selection produces

evolutionary change because it changes the genetic composition of populations. A variety of other mechanisms can also produce evolutionary change. For example, suppose that 65% of the eye-color genes in a population were for individuals with blue eyes and 35% of the genes were for brown eyes. If most of the immigrants entering the population carried the blue gene, the overall composition might change from 65% blue to 70% blue.Evolution occurs in populations, not in individuals. Although mechanisms exist for individual bacteria to change

their genetic composition, multicellular organisms do not change their genetic characteristics and therefore cannot evolve. Natural selection does not act on an individual to make it better adapted to its environment.

Example of Natural Selection : The Peppered Moth There are two forms of the peppered moth in England- a dark-colored form and a light form.In the early 1800's, most moths were the light form. The first dark form was reported in 1848. The dark form

increased in frequency during the last half of the 1800s. By 1895, 98% of the Moths in Manchester were the dark form.The increase in the dark form of the moth occurred at a time of rapid industrialization in England- the industrial

revolution. During this time, an increase in the amount of coal-burning factories caused widespread pollution. The pollution killed light-colored lichens, causing the trees to be darker. The trees in polluted areas were also covered with dark soot.

Human Body SystemsThe Heart: Belongs to the circulatory systemTrace A Drop Of Blood:

Deoxygenated blood from the body enters the right atrium. It then flows through into the right ventricle.

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Blood flows into the pulmonary artery. This branches immediately, carrying blood to the right and left lungs. Here the blood gives up carbon dioxide and takes on a fresh supply of oxygen.

Four pulmonary veins, two draining each lung, carry oxygenated blood to the left atrium of the heart. From the left atrium, Blood flows into the left ventricle. The oxygenated blood then leaves the left ventricle and goes to the body.

Right side of the heart is oxygen-poor Left side of the heart is oxygen-rich

Human Body Systems

SYSTEMS FUNCTIONS ORGANS Interacts with other systems

Respiratory

intake of oxygen and removal of carbon dioxide from body

lungs, nasal passages, bronchi, pharynx, trachea, diaphragm, bronchial tubes

Circulatory system – blood helps transport oxygen from the lungs and CO2 to the lungs

Nervous

Control s body activities and the reaction to stimuli.Maintains a constant internal balance within the body. (Homeostasis)

spinal cord, brain, nerves, skin, eyes, ears, tongue, nose

Interacts with all of the systems

Digestivebreak down of food and absorption for use as energy

stomach, liver, teeth, tongue, pancreas, intestine, esophagus

Circulatory system: nutrition is delivered. Excretory system: rids body of waste

Excretory controls water and salt balance

kidneys, bladder ureters, skin

Circulatory system: Filters waist from the blood through the kidneysDigestion system: food is broken down and waste is removed

Endocrineproduction of hormones and body regulation

pituitary gland, adrenal gland, thyroid gland, gonads

Excretory system: hormones help regulate and tell the body to eliminate waste.Circulatory system: Hormones use this system as a means of transportation.

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Skeletal

Protection, support, produces some immune cells and red blood cells

bonesMuscular system – enables the body to move.

MuscularMovement,Aid organs to perform correctly

Muscles(3 types: smooth-found near organs, Cardiac- heart, striated or skeletal muscles)

Circulatory system: enables the heart to pump blood.Digestion system: enables food to be digested.Excretory system: aid in ridding the body from waste.

Circulatory

transport of nutrients, metabolic wastes, water, salts, and disease fighting cells

blood, blood vessels, heart, lymph

Respiratory System: provides the blood with oxygen and removes the carbon dioxide

Integumentary

protection of body from injury and bacteria, maintenance of tissue moisture, holds receptors for stimuli response, body heat regulation

skin

Excretory system: Sodium is released through the skinNervous System: allows the skin to “feel”

Lymphatic(Immune)

Collects tissue fluid and returns it to the blood. Protect your body from harmful microorganismsdefend itself againstdisease causing organisms

Lymph, Lymph nodes, Tonsils, Spleen, Thymus

Circulatory system: transports the immune cellSkeleton: The bone marrow makes certain immune cells

Living EarthBiosphere—the part of Earth that supports life

1. The top portion of Earth’s crust, all the waters on Earth’s surface, and the surrounding atmosphere2. Made up of different environments that is home to different kinds of organisms

Ecosystem—all the organisms living in an area and the nonliving features of their environment1. Ecology is the study of interactions that occur among organisms and their environment.2. A population is made up of all the organisms in an ecosystem that belong to the same species.3. A community is all the populations in an ecosystem.

Habitat—the place in which an organism lives1. Must provide the kinds of food, shelter, temperature, and moisture the organism needs to survive2. Example: trees are the woodpecker’s habitat

Competition—two or more organisms seek the same resource at the same time1. Competition for food, living space, or other resources can limit the population.

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2. Competition is usually most intense between members of the same species.Population size—indicates whether a population is healthy and growing

1. Population density—the size of a population that occupies a specific area2. Elements that affect population size

a. Limiting factor—any living or nonliving feature that restricts the number of individuals in a populationb. Carrying capacity—the largest number of individuals of one species that an ecosystem can supportc. Biotic potential—the maximum number of offspring that parent organisms can produced. Birth and death ratese. Movement of organisms into or out of an area

Exponential growth—the larger a population becomes, the faster it grows the death rate to increase, or the birth rate to decrease? Are organisms moving out of the area?

Sun—source of energy that fuels most life on EarthProducers—organisms that use an outside energy source to make energy-rich molecules

a. Most producers use the Sun and contain chlorophyll, a chemical required for photosynthesis.Consumers—organisms that cannot make their own energy-rich molecules; they obtain energy by eating other organisms.

Herbivores, like deer and rabbits, eat plants.Carnivores, like frogs and lions, eat animals.Omnivores, like pigs and humans, eat both plants and animalsDecomposers, like earthworms and bacteria, eat dead organisms Decomposers are important because they help recycle nutrients. Examples of decomposers include bacteria and fungi as well as other organisms.

Food chain—a model that shows the feeding relationships among the organisms in an ecosystem. The arrow ALWAYS points at the animal that is receiving the food or energy.

Click here to play the PowerPointFood Chains and Food Webs: Energy flows through the ecosystem in food chains. Food chains begin with the sun and green plants. Plants collect use and store energy from the sun. Herbivores get their energy from the plant material they eat. As energy is moved from one organism to another, some of it is lost to the environment as heat. Plant and animal respiration and growth account for some of this lost energy. Food chains are used to show part of the complex way in which energy is transferred in ecosystems. Organisms seldom eat just one kind of plant or animal. The many interactions of plants and animals in food chains, when connected, form a food web. By following the path of energy from

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the sun, you can see how the plants and animals are all interconnected. You should be able to identify several different food chains within a food web. Energy Pyramid: Most of the energy obtained by organisms when they eat is used to move, grow, reproduce, and carry out other life activities. This means that only some of the energy will be available to the next organism in the food web. A diagram called an energy pyramid shows the amount of energy that moves from one feeding level (trophic level) to another in a food web. The organisms at each level use some of the energy to carry out their life processes. The most energy is available at the producer level. At each level in the pyramid, there is less available energy than at the level below. An energy pyramid gets its name from the shape the diagram naturally takes; wider at the base and narrower at the top, resembling a pyramid. In general, only about 10 percent of the energy at one level of a food web is transferred to the next, higher, level. The other 90 percent of the energy is used for the organism's life processes or is lost as heat to the environment. Because of this, most energy pyramids only have three or four feeding levels. Since 90 percent of the energy is lost at each level there is not enough energy to support any more than three or four feeding levels. The organisms at higher feeding levels of an energy pyramid do not necessarily require less energy to live than organisms at lower levels. Since so much energy is lost at each level, the amount of energy in the producer level limits the number of consumers the ecosystem can support. As a result, there usually are few organisms at the highest level in a food web and increasingly more organisms as you move down the energy pyramid to successively lower feeding levels.

Symbiosis—any close relationship between speciesMutualism—a symbiotic relationship in which both species benefit (+/+)Commensalism—a symbiotic relationship in which one organism benefits and the other is not affected (+/0)Parasitism—a symbiotic relationship in which one organism benefits and the other is harmed (+/-)

Niche—a species’ unique requirements for survival, including its habitat and food, and how it avoids danger, finds a mate and cares for its young

Levels of Organization

How Ecosystems ChangeEcological succession—normal, gradual changes that occur in the types of species that live in an area

1. Primary succession begins in a place without soil.a. Starts with pioneer species such as lichens, that can grow on rockb. New soil forms as weather and erosion break down rock.c. Decaying plants add organic material to new soil.

2. Secondary succession begins in a place that has soil and once had living organismsa. Example: after a fire or removal of buildingsb. Occurs faster and has different pioneer species than primary succession

Climax community—stable stage of ecological diversity and balance

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Cell Tissue OrganOrgan system

System

Organism Population

CommunityEcosystem

BiomesFactors that affect biomes climate: temperature and precipitationMajor biomes—large areas with similar climates and ecosystems

Tundra—cold, dry, treeless regionPermanently frozen soil called permafrostAverage temperature: –12°CAverage precipitation is less than 25 cm per year.Plants: mosses, grasses, small shrubs, lichens Animals: insects, ducks, geese, other birds, mice, arctic hares, reindeer

Taiga—cold forest of mostly evergreen treesSoil thaws in the short summer.Precipitation: mostly snow, 35 cm–100 cm per year

Temperate deciduous forests—region with four seasons, mostly trees that lose their leaves in autumnTemperatures range from below freezing in winter to 30°C or more in summer.Precipitation: throughout the year, 75 cm–150 cm per year

Temperate rain forest—tall trees with needlelike leavesAverage temperature: 9°C–12°CPrecipitation: 200 cm–400 cm per year

Tropical rain forests—the most biologically diverse of all biomesAverage temperature: 25°CPrecipitation: 200 cm–600 cm per yearFour zones: forest floor, understory, canopy, emergentHuman impact: Habitats being destroyed by farmers and loggers

Desert—driest biome, supports little plant lifeTemperatures: vary from hot to coldPrecipitation: less than 25 cm per yearSoil: thin, sandy, or gravellyPlant: cactusAnimal: kangaroo rat

Grasslands—prairies or plains, dominated by grassesTemperatures: temperate or tropicalPrecipitation 25 cm–75 cm per year; dry season

Nitrogen CycleNitrogen is used by life forms to carry out many of the functions of life. This element is especially important to plant life. Yet nitrogen in its gaseous form is almost entirely unusable to life forms. It must first be converted or ‘fixed’ into a more

usable form. The process of converting nitrogen is called fixation. There are specialized bacteria whose function it is to fix nitrogen, converting it, so that it can be used by plants. There are still other bacteria that do the reverse. That is, they return nitrogen to is gaseous form. After nitrogen is fixed, it can be absorbed, and used by plants, and subsequently by animals. The process of nitrogen being fixed, used by plants and animals, and later returned to the atmosphere is referred to as the nitrogen cycle.

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Carbon CycleCarbon is extracted from the atmosphere by plants through the process known as photosynthesis. This carbon is combined with other elements in complex ways to form organic molecules important to life. This carbon is later transferred to animals that consume or eat plants. When plants and animals die, much of their carbon is returned to the atmosphere as the organisms decompose. Every so often, a plant or animal does not decompose right away. Their bodies are trapped, in locations where decomposition can simply not take place. This is most common at the bottom of oceans and seas, where the life forms become buried by sand. Instead of returning to the atmosphere, the carbon from these life forms is trapped within the Earth. Over millions of years more and more of the carbon on Earth have been trapped in this manner. Today, almost 99% of all the carbon on Earth has been locked up deep within the Earth. As rocks weather, this carbon is slowly released back into the atmosphere, creating a balance. For the past several hundred million years, the amount of carbon being locked up in the Earth, and the amount being released by weathering rocks was almost perfectly balanced. This important balance has been altered significantly in the past century, as humans have begun using fossil fuels to produce energy.

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