Download Name Period ______ Study Guide for the 2nd Semester Final Exam

Name ___________________________________________________________________________ Period ___________
Study Guide for the 2nd Semester Final Exam
Chapter 11
Reproduction of
Organisms –
Page 424
Diploid Cells
1. Organisms that reproduce sexually make two kinds of cells—body cells
and sex cells.
Haploid Cells
1. Sex cells are haploid; they have only one chromosome from each pair of
chromosomes.
2. In meiosis, one diploid cell divides and makes four haploid cells.
Why is meiosis
important?
1. Meiosis forms sex cells with the correct haploid number of
chromosomes. This maintains the correct diploid number of chromosomes
in organisms when sex cells join.
2. Meiosis creates genetic variation by producing haploid cells.
How do mitosis
and meiosis
differ?
1. During mitosis and cell division, a body cell and its nucleus divide once
and produce two identical cells.
2. During meiosis, a reproductive cell and its nucleus divide twice and
produce four cells two pairs of identical haploid cells.
Advantages of
Sexual
Reproduction
1. Sexual reproduction produces offspring that have a new combination of
DNA. This results in genetic variation among individuals.
2. Genetic variation gives individuals within a population slight
differences that might be an advantage if the environment changes.
3. Selective breeding has been used to develop desirable traits in plants and
animals.
Disadvantages of
Sexual
Reproduction
1. One disadvantage of sexual reproduction is that organisms have to grow
and develop until they are mature enough to produce sex cells.
2. Another disadvantage is that searching for a mate takes time and energy
and might expose individuals to predators, diseases, or harsh
environmental conditions.
What is asexual
reproduction?
1. In asexual reproduction, one parent organism produces offspring
without meiosis and fertilization.
2. Because the offspring of asexual reproduction inherit all their DNA
from one parent, they are genetically identical to each other and their
parent.
Types of Asexual
Reproduction
1. Cell division in prokaryotes is known as fission.
2. During fission, DNA is copied and the cell splits to form two identical
offspring. The original cell no longer exists.
3. In budding, a new organism grows on the body of its parent by mitosis
and cell division. When the bud becomes large enough, it can break from
the parent and live on its own.
4. Regeneration occurs when an offspring grows from a piece of its parent.
a. Sea stars, sea urchins, sea cucumbers, and planarians can reproduce
through regeneration.
b. Many animals can regenerate damaged or lost body parts. This is not
reproduction; new individuals are not produced.
5. Vegetative reproduction is a form of asexual reproduction in which
offspring grow from a part of a parent plant.
6. Cloning is a type of asexual reproduction developed by scientists and
performed in laboratories. It produces identical individuals from a cell or
from a cluster of cells taken from a multicellular organism.
7. Because all of a clone’s chromosomes come from one parent, the clone
is a genetic copy of its parent.
8. Asexual reproduction enables organisms to reproduce without a mate.
9. Asexual reproduction also enables some organisms to rapidly produce a
large number of offspring.
10. Asexual reproduction produces offspring that are genetically identical
to each other and to their parent. This results in little genetic variation
within a population.
11. Genetic variation is important because it can increase an organism’s
chance of surviving if the environment changes.
12. Genetic changes, called mutations, can occur and then be passed to
offspring; this can affect the offspring’s ability to survive.
Chapter 12
Genetics – Page
458
Early Ideas about 1. Heredity is the passing of traits from parents to offspring.
Heredity
2. Genetics is the study of how traits pass from parents to offspring.
What controls
traits?
1. Inside each cell is a nucleus that contains threadlike structures called
chromosomes.
2. Mendel’s factors are parts of chromosomes, and each cell in offspring
contains chromosomes from both parents.
3. A gene is a section on a chromosome that has genetic information for
one trait.
4. The different forms of a gene are called alleles.
5. Geneticists refer to how a trait appears, or is expressed, as the trait’s
phenotype.
6. The two alleles that control the phenotype of a trait are called the trait’s
genotype.
a. In genetics, uppercase letters represent dominant alleles, and
lowercase letters represent recessive alleles.
b. When two alleles of a gene are the same, its genotype is homozygous.
c. If two alleles of a gene are different, its genotype is heterozygous.
Modeling
Inheritance
1. To create a Punnett square, you need to know the genotype of both
parents.
2. If you count large numbers of offspring from a particular cross, the
overall ratio will be close to the ratio predicted by a Punnett square.
3. A pedigree is a diagram that shows phenotypes of genetically related
family members. It also gives clues about their genotypes.
The Structure of
DNA
1. Genes provide directions for a cell to assemble molecules that express
traits such as eye color or seed shape.
2. Chromosomes are made of proteins and deoxyribonucleic acid, or DNA,
which is an organism’s genetic material.
3. Strands of DNA in a chromosome are tightly coiled like a telephone
cord.
4. The work of several scientists revealed that DNA is shaped like a
twisted ladder, or a double helix.
5. DNA is made of nucleotides, which are molecules made of a nitrogen
base, a sugar, and a phosphate group.
6. There are four nitrogen bases—adenine (A), cytosine (C), thymine (T),
and guanine (G).
7. Replication copies a DNA molecule to make another DNA molecule. It
produces two identical strands of DNA.
Making Proteins
1. The DNA of each cell carries a complete set of genes that provides
instructions for making all the proteins a cell requires.
2. The process of making mRNA from DNA is transcription.
3. The process of making a protein from RNA is called translation.
Mutations
1. A change in the nucleotide sequence of a gene is a mutation.
2. Because mutations can change proteins, they can change traits.
3. Mutations can have negative effects, positive effects, or no effect on
traits.
Chapter 13 The
Environment and
Change Over
Time – Page 506
The Fossil Record
1. Fossils are the preserved remains or evidence of once-living organisms.
2. All the fossils ever discovered on Earth make up the fossil record.
3. Fossils help scientists figure out what species that no longer exist looked
like when the organisms were alive.
Determining a
Fossil’s Age
1. Scientists cannot date most fossils directly. Instead they usually find the
age of the rocks around the fossils.
2. In relative-age dating, scientists determine the relative order in which
rock layers were deposited.
a. In an undisturbed rock formation, the older layers of rock are below
the younger layers of rock.
b. Relative-age dating has helped scientists figure out the order that
species have appeared on Earth.
3. Absolute-age dating is more precise than relative-age dating and
involves radioactive isotopes that decay to become stable isotopes over
time.
Extinctions
1. When the last individual organism of a species dies, an extinction has
occurred.
a. Extinctions can occur if the environment changes quickly; for
example, as the result of a meteorite impact.
b. Extinctions can also occur if the environment changes gradually; for
example, as a result of the formation of mountain ranges.
2. The fossil record contains clear evidence of the extinction of species
over time as well as evidence of the appearance of many new species.
Darwin’s Theory
1. Darwin knew that in any species, members of the same species each
have slight differences, called variations.
2. Natural selection is the process by which populations of organisms with
variations that help them survive in their environments live longer,
compete better, and reproduce more than populations that do not have the
variations.
Adaptations
1. An adaptation is a characteristic of a species that enables the species to
survive in its environment.
2. Scientists classify adaptations into three categories.
a. Structural adaptations involve shape, size, color, and other physical
features; the length of a Galápagos tortoise species’ neck is an example
of this type of adaptation.
b. Behavioral adaptations involve the way organisms act; hunting at
night is an example of this type of adaptation.
c. Functional adaptations involve internal body systems that affect
organisms’ biochemistry; expanding blood vessels that cool a
jackrabbit’s blood is an example of this type of adaptation.
Chapter 14
Interactions of
Living Things –
Page 548
Populations
3. The living and the nonliving parts of the environment are always
changing; species that cannot adapt to such changes will become extinct.
1. A population is all the members of one species that live in an area at one
time.
2. The size of a population can increase or decrease in response to changes
in abiotic or biotic factors in the environment.
a. Limiting factors limit the growth of a population. One factor is the
lack of sufficient resources such as water; some individuals cannot
survive under these circumstances.
b. Factors such as predation, competition, and disease are examples of
limiting factors.
3. Biotic potential is the potential growth of a population if it could grow
in perfect conditions with no limiting factors.
4. Carrying capacity is the largest number of individuals of a species that
an ecosystem can support over time.
5. The limiting factors of an area determine the area’s carrying capacity.
6. Overpopulation occurs when a population’s size becomes larger than the
ability of the area to support it.
Symbiotic
Relationships
1. A symbiotic relationship occurs when two different species live together
in a close relationship over a long period of time.
a. Mutualism is a symbiotic relationship in which two species in a
community help each other.
b. Parasitism is a symbiotic relationship in which one species (the
parasite) benefits while another (the host) is harmed.
c. Commensalism is a symbiotic relationship in which one species
benefits and the other is not helped or harmed.
A. Energy Flow
1. Organisms get energy either by using light or chemical energy to make
food or by eating other organisms.
Organisms and
Energy
1. Producers change the energy available in their environment into food
energy.
2. Plants, algae, and some microorganisms use a chemical process called
photosynthesis and change light energy from the Sun into food energy.
3. Some producers use chemosynthesis to change chemical energy into
food energy.
4. Consumers cannot make their own food and get energy by eating other
organisms.
a. Herbivores consume only producers.
b. Carnivores consume only other consumers.
c. Omnivores eat other consumers and producers.
d. Detritivores eat dead plant or animal material.