Bio I Q3 EXAM

What differences found in species' population does natural selection act on?

different phenotypes

What makes these different phenotypes possible within a species population?

genetic variation

Genetic variation is species' populations results in more members of the species being able to do what?

survive a changing environment

How is genetic variation stored in a species' population?

gene pool

The gene pool for all the individuals within a population includes what from all the individuals of that population?

combined alleles

What are the three main sources of genetic variation?

mutations, recombination, hybridization

What do mutations result in a random change in? What can these mutations form?

DNA of a gene; a new allele

During what process do new allele combinations form in offspring through parental alleles changing places?

recombination

In what process of genetic replication does recombination occur most often?

meiosis

What term is given to the crossing of two different species that share common genes?

hybridization

When the value of the distribution of traits is shown on a graph, what term describes the most common traits?

mean

Which type of phenotypes are less common in species' phenotype distribution?

extreme phenotypes

How are extreme phenotypes represented on a graph showing trait distribution?

a drop on each side of the bell-curve

What would result in less common phenotypes being more advantageous to a population?

environmental conditions changing suddenly

What are the three different paths through which natural selection can change the distribution of a trait?

directional, stabilizing, disruptive

What becomes more common in directional selection?

extreme phenotypes

Which kind of phenotype becomes more common in the species' population during stabilizing selection?

intermediate

What happens to the most common traits in a species' population during disruptive selection?

dramatically decline over time

Gene flow occurs when individuals of the same species do what?

move between populations

What increases as a result of gene flow?

genetic variation

What effect does genetic drift have on the genotypes of a species' population?

loss of genetic diversity

What are two main processes of genetic drift?

bottleneck, founder

Both sexes of a species benefit from their offspring being able to do what?

survive

What does a female ensure for her offspring by choosing the best mate possible?

best genetics possible

What are the two types of sexual selection?

intersexual, intrasexual

Males of a species convince females that they possess what two qualities during intersexual selection?

healthy and good genetic quality

Gene

specific region of DNA that codes for a particular protein

Allele

any of the alternative forms of a gene that occurs at a specific place on a chromosome

Genome

all of the organisms genetic material

Genotype

collection of all of an organism's genetic information that codes for traits

Phenotype

collection of all of an organism's physical characteristics

Dominant

allele that is expressed when two different alleles are present in an organism's genotype

Recessive

allele that is not expressed unless two copies are present in an organism's genotype

Testcross

cross between an organism with an unknown genotype and an organism with a recessive phenotype

Crossing over

exchange of genetic material between homologous chromosomes during prophase I of meiosis

What term is given to the specific location of genes on a chromosome?

locus

What are alternative forms of a gene called?

allele

How many alleles do cells have for each gene?

2

Which type of allele is expressed when 2 different alleles or 2 dominant alleles are present on a chromosome?

dominant

Which type of allele is expressed when 2 copies of a recessive allele are present on a chromosome?

recessive

What is commonly done by scientists while studying genetics?

focusing on a single trait

Besides genotype, what also interacts with genes and affects their expression?

phenotype

What was the profession of R.C, Punnett?

poultry geneticist

What type of system did Punnett develop for predicting all possible genotypes resulting from a genetic cross?

punnett square

By counting the number of squares in a genetic combination, what can be figured concerning genotypes?

ratio

What process restores the diploid number in offspring?

fertilization

List the three types of monohybrid crosses?

homoXhomo; heterXheter; heterXhomo

What type of phenotype must an organism have in order for a testcross to be necessary?

recessive

What was the phenotypic ration that Gregor Mendel consistently obtained in the second generation of breeding?

9:3:3:1

What name is given to Medndel's second law of genetics?

law of independent assortment

According to the law of independent assortment, how do allele pairs separate during meiosis?

independently

Which type of outcomes are predicted through the use of the mathematics called probability?

heredity patterns

What is a major advantage of sexual reproduction that is produced within a species?

genetic variation

In the formation of gametes, how many different possible human chromosome combinations are there?

8 million

What are mixed during the joining of gametes during fertilization?

alleles

How many possible genetic combinations are there i the joining of two human gametes?

70 trillion

What is ensured for organisms through sexual reproduction? What does this result in for the organism?

unique combination; unique phenotypes

What is another term for the process of ensuring genetic diversity called crossing over?

recombination

When does crossing over occur?

prophase I of meiosis I

What affects the likelihood of weather genes are separated when crossing over happens?

the farther apart the genes are

Which kind of genes tend to be inherited together?

closely located

What have scientists been able to build for many species by exploring relationships between many genes?

genetic map

Probability

likelihood that a particular event will happen

Somatic Cells

cell that makes up all of the body tissues and organs, except gametes

Gamete

sex cell; an egg or a sperm cell

Autosome

chromosome that contains genes for characteristics not directly related to the sex of the organism

Sex Chromosome

chromosome that directly controls the development of sexual characteristics

Fertilization

fusion of an egg and sperm cell

Meiosis

form of nuclear division that divides a diploid cell into haploid cells; important in forming gametes for sexual reproduction

Gametogenesis

process by which gametes are produced through the combination of meiosis and other maturational changes

Trait

characteristic that is inherited

Genetics

study of the heredity patterns and variation of organisms

Cross

mating of two organisms

What are the two major groups of cells that make up organisms?

somatic and germ clls

For each somatic cell, what does each species have a characteristic number of?

chromosomes

How many chromosomes do humans have?

46

How many pairs of chromosomes do humans have?

23

Which type of cells make up most of an organism's body tissues and organs?

somatic cells

Which two types of gametes make up the germ cells of an organism?

egg and sperm

What two characteristics do homologous chromosomes have in common?

length & general apperance

What letters are given to the 23rd sex chromosome in the human genome?

X & Y

Sexual reproduction involves the fusion of what?

gametes(sperm & egg)

Which type of body cells are diploid?

somatic

Which type of body cells are haploid?

gametes

What happens to the nucleus during the process of meiosis?

divides & makes four haploid cells

In meiosis, how many phases are there to each round of cell division?

4

Which type of chromosome are divided in meiosis I?

homologous chromosome

Which type of chromosome are divided in meiosis II?

sister chromatid

What type and number of cells are produced in meiosis I?

two cells with 23 duplicated chromosomes

Is DNA duplicated during meiosis I?

NO

What type of cells are produced at the end of meiosis II?

4 haploid cells

Differences in the final stages of gametogenesis are based upon what?

gender of the parent

Which type of cell contains the DNA of the male gamete?

sperm cell

Which cell organelle provides sperm cells with the energy needed for the cell's survival and movement?

mitochondria

Which type of cell contains the DNA of the female gamete?

egg cell

For mammals, when does egg formation begin inside the female body?

before birth inside the embryo

What term is given to distinguish characteristics that are inherited?

traits

Who is given credit for establishing the study of genetics as a modern science?

Gregor Mendel

What was Mendel's profession?

austrian monk

What type of plants did Mendel use in his genetic studies?

pea plants