Genetics

A proposed explanation for an observation which has not been experimentally tested.

hypothesis

Indicate the correct designation of the paired sex chromosomes.

male: XY Female: XX

Twenty-three is the haploid number of chromosomes in man.

true

The process of crossing two organisms, both having homozygous genes for the same trait. i.e. (ZZ x ZZ) or (zz x zz).

true-breeding

A monohybrid cross is made between plants:

which differ in only one trait

How many chromosome pairs are in humans?

23

How many chromosome pairs are in Drosophila?

4

The stage in the second meiotic division where sister chromatids of a chromosome split and migrate to opposite poles.

Anaphase II

Which scriptures describe a biologic law of reproduction for which no exception has ever been documented?

Genesis 1:12, 1:24

The parental generation for a given cross.

P1 generation

Genes which are "linked" together:

are found on a particular chromosome

Any pair of chromosomes other than the sex chromosome.

autosome

A structure on the chromosome that holds a pair of chromatids together during replication.

centromere

A double-stranded chromosome following replication attached by a centromere.

chromatid

A "threadlike" molecule in the nucleus, composed of DNA. A chromosome possesses one allele for a given trait, therefore chromosomes occur in pairs. Each originates from the male and female gamete (parent).

chromosome

The behavior of chromosomes explains the inheritance of genes.

chromosome theory

Each P1 parent of a monohybrid cross has completely identical genes.

false

A reproductive cell produced by the male or female parent, which contains the haploid number of chromosomes.

gamete

According to scripture, all known occurrences in the laboratory of the Earth have shown that each kind of organism is limited to reproducing a similar .

kind

A type of cell division used to produce gametes and there is a reduction in the chromosome number from the diploid to the haploid number.

meiosis

The breeding of two organisms which differ in a single trait.

monohybrid cross

Where more than two alternatives for a gene exist

multiple alleles

The outward appearance of the organism which is the product of gene action.

phenotype

The chance that a given event will occur

probability

The probability of two independent events occurring together is the _____ of the probability of each event occurring separately.

product

The organism, which possesses both male and female gametes, brings the two genetically identical gametes together to produce offspring.

self-fertilization

The production of haploid male gametes by the male parent.

spermatogenesis

A number of threadlike filaments formed between poles of the cell during cell division to which the centromeres of chromosomes attach; used to pull chromosomes apart and segregate them during anaphase.

spindle fibers

Why did Mendel prevent his plants from self-pollinating?

to control the crossing of the traits

A genetic characteristic of the individual.

trait

A reptile has never been observed to give birth to a bird

true

Meiosis consists of __________ cell divisions with only one duplication of _________ . This division results in ________ daughter cells, each with ____ set of chromosomes. This division represents a reduction in chromosomes; that is, the diploid chromosome number of the parent cells is reduced to the ________ number of the daughter cells.

2 chromosomes 1 haploid

The stage on the first meiotic division when the homologous chromosomes move to opposite poles but the sister chromatids remain together.

Anaphase I

A giant molecule consisting of the sugar deoxyribose, phosphates and nitrogen bases; contains the coded genetic information.

DNA

First filial generation; the first generation from a given cross.

F1 generation

The seeds collected from the first generation monohybrids are called:

F1 or hybrid

Second filial generation; the second generation resulting from interbreeding or fertilization from other F1 members.

F2 generation

What is meant by homologous chromosomes?

Genes alleles are found in matched chromosome pairs

The stage in the first meiotic division where the homologous chromosomes line up as a pair, forming a tetrad of chromatids, at the equator of the cell.

Metaphase I

The stage in the second meiotic division where the chromatid pair lines up at the equator of the cell..

Metaphase II

Members of a gene pair separate during meiosis and are found in separate gametes

Principle of segregation

A grid system used to predict possible combinations of genes due to random fertilization.

Punnett square

The stage of the first meiotic division where the cell divides into two cells each containing one member of each pair of homologous chromosomes.

Telophase I

The stage of the second meiotic division when the cell divides into two cells with each being haploid; these cells become the gametes.

Telophase II

Pollen must land on all of the silk strands for the ear to fill out completely with kernels.

True

Each trait characteristic of a plant is determined by:

a pair of genes

The genotype represents:

a paired combination of genes

Somatic cells include:

all the cells of an organism except the gametes

Alternative forms for a specific gene.(either dominant or recessive)

allele

A condition where non-sister chromatid of homologous chromosomes exchange genes.

crossing over

Variation from the predicted values.

deviation

Breeding of individuals which have genes for two different characteristics.

dihybrid cross

Both members of a pair of chromosomes are present.

diploid

In a pair of genes, one may prevent the allele from being expressed.

dominant

The characteristic which resulted from a monohybrid cross is the ____________ trait.

dominant

A _______ trait completely hides or masks the presence of its counterpart, the ______ trait.

dominant recessive

The controlling influence which produced distinct ratios of traits was called ___________ by Mendel and are known today as _________

factors, genes

Each chromosome represents a single gene.

false

Gametes are associated with diploid chromosomes.

false

Gregor Mendel was a respected, professional scientist who introduced the science of biology.

false

Heterozygous genes will always display a dominant trait

false

Somatic cells are haploid

false

The heredity principles developed by Mendel apply only to plants.

false

A portion of DNA which codes a specific hereditary trait.

gene

W.S. Sutton proposed that the ________ are located on _______ and these factors segregate during ______ and the production of gametes.

genetic factors chromosomes meiosis

The genes present in an organism.

genotype

The blending of two traits in a heterozygous individual

incomplete dominance

An explanation for events which is supported by the results on many experiments by a large number of investigations.

law

The presence of different genes on the same chromosome.

linkage

What can be expected for the recessive trait of monohybrids from the F2 generation?

none of the above

Process of development of haploid female gametes.

oogenesis

The outward appearance of a particular trait is called the

phenotype

One of three small cells produced during oogenesis, each contain the haploid number of chromosomes.

polar body

Transfer of pollen, male gamete, in plants to the stigma which contains the female gamete.

pollination

Genetics experiments on the breeding of plants or animals are based on the laws of

probability

A phenotype (trait) resulting from homozygous genes from the offspring of true breeding.

pure-bred

A gene or trait which is masked when a dominant allele is present.

recessive

In addition to covering each pea plant to prevent pollination from other pea plants in his garden, what did Mendel do to prevent self-pollination?

remove the stamen

The reduction of a gene pair to an allele during the formation of a gamete is called the principle of

segregation

Mendel's first principle, the principle of _________, states that in the process of forming gametes, the inheritance factors for any trait always _________.

segregation segregate

The breeding of an individual which possesses the dominant trait to a homozygous recessive for that trait.

test cross

During metaphase I the two pairs of chromatids of the homologous pair of chromosomes comes together; crossing-over can occur at this time.

tetrad

The form of the hypothesis after it has been tested and found to be supported by the data collected as the explanation for the observation.

theory

A scientific law may be used to predict the outcome of experiments.

true

All members of each species have the same number of chromosomes.

true

Chromosomes are located in the nucleus of the cell.

true

The stage in the first meiotic division where the doubled chromosomes become visible and nuclear membrane disappears.

Prophase I

A sex chromosome; in human males only one is present and in females two are present.

X chromosome

A sex chromosome found in males; influencing the degree of maleness.

Y chromosome

Give an example of how you could determine whether or not a trait was displaying incomplete dominance. What would you do? What would your results have to be for the trait to be incomplete dominant?

One could determine whether or not a trait was displaying incomplete dominance by observing the traits of the parent individuals. If the new trait was different from both of the parent traits and seemed to be a mixture, one could assume that incomplete dominance has occurred. A good example of this is the Snapdragon Flower. If a red flower was crossed with a white flower, it would produce an F1 generation of pink flowers. With the trait observed being the color, one can see that the F1 generation exhibits a combination of the original traits. This can be tested by crossing two F1 generations. If this were done in the Snapdragon, two pink flowers would make an F2 generation with a ratio of 1/4 red:1/2 pink: 1/4 white. This causes incomplete dominance because neither gene is dominant over the other.

One member of a pair of homologous chromosomes is present, such as in a gamete.

haploid

Meiosis is associated with the:

haploid number of chromosomes gamete cells

Refers to a pair of genes for a specific trait in an organism which are different.

heterozygous

Refers to a pair of genes in an organism which are identical in the way they influence a trait.

homozygous

An offspring from a cross between parents which has different phenotypes for a specific trait.

hybrid

The difference between appearance and genetic makeup has led to the development of two terms to distinguish the two conditions. The appearance of the organism for the trait is called _________; the actual genetic makeup is called ________.

phenotype genotpe

Chromosomes other than sex chromosomes are autosomes.

true

Each chromosome usually contains multiple genes.

true

Experiments and observations verify scientific laws.

true

Meiosis is the process that results in the production of the haploid number of chromosomes.

true