Exam 3 Life 102 CSU Erik Arthun

In eukaryotic cells, chromosomes are composed of

DNA and proteins

DNA is replicated during which phase of the cell life?

S

The somatic cells produced from a single-celled zygote divided by which of the following processes?

Mitosis and cytokinesis

A. cell containing 50 chromatids at metaphase of mitosis would (at the completion of mitosis) produce two nuclei each containing how many chromosomes?

25

During which phase of mitosis do sister chromatids separate and the two new chromosomes then move to opposite ends of the dividing cell?

Anaphase

Through a microscope, you can see a cell plate beginning. to develop across the middle. of a cell, and nuclei forming on ether side of the cell plate. This cell is most likely

A plant cell in the process of cytokinesis

Starting with a fertilized egg (zygote) a series of 6 cell divisions would. produce an early embryo with how many. cells?

64

What is the final result of mitosis in a human?

Genetically. identical 2n somatic cells

If cells have been diverted in to G0 phase of the cell cycle, what does this mean?

They are not dividing

Asexual reproduction occurs during

mitosis

In animals, meiosis results. in gametes, and fertilization results in

zygotes

If 2n=60 tomatoes, how many chromosomes do gamete cells of tomato plants have?

30

You inherited two copies of chromosome #8 from your parents (one from your mother, and one from your father). WE refer to these paired chromosomes as "homologous chromosomes". Which of the following is true of homologous chromosomes?

They contain genes of the same traits

Crossing over normally takes place during which of the following processes?

Meiosis 1

Which of the following happens at the conclusion of meiosis I?

Homologous chromosomes of a pair are separated from each other

Sister chromatids separate from each other during

mitosis and meiosis II

Which of the following is true for both mitosis and meiosis

the cell's DNA is duplicated before cell division starts

From perspective what is the main advantage of sexual reproduction

It creates offspring that are genetically diverse which is advantageous in a changing environment

What are alleles?

versions of a gene

It was important that Mendel examined not just. the F1 generation in his breeding experiments, bu the F2 generation as well, because

Parental traits that were not observed in the F1 generation reappeared in thee F2 generation

Why did the F1 offspring of Mendel's classic pea cross always look like on of the two parental varieties?

One allele was completely dominant over another

Mendel's observation of the segregation of alleys in gamete formation has its basis in which of the following phases of cell division?

Anaphase I of meiosis

Which of the boxes marked 1-4 correspond to plants with dark leaves?

1,2 and 3

Which of the boxes marked 1-4 corresoond to plants with a heterozygous genotype

2 and 3

In certain rodents, dark-colored fur is dominant to light colored fur. If two heterozygous rodents were to mate, what is the probability that the offspring will have light colored fur?

1/4

When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the dominant phenotype?

50%

Which of the following is an example of polygenic inheritance

Skin pigmentation in humans

Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. The relationship between genes S and N is an example of _____.

Epistasis

Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and others pink flowers. This can be best explained by which of the following?

Environmental factors such as soil pH

The human X and Y chromosomes...

include genes that determine an individual's sex

Males are more often affected by sex linked trait than females because

males have only one copy of the X chromosomes

A man who carries an allele of an X-linked gene will pass it on to

All his daughters

Normally, only female cats have the "tortoiseshell" phenotype because

A male inherits only on of the two X-linked genes controlling hair color

A recessive allele on the X chromosome is responsible for red-green color blindness in humans. A woman with normal vision ( whose father is color blind) marries a color blind male. What is the probability that this couple's first child will be color blind?

1/2

What is the reason that closely-linked genes are typically inherited together?

They are located close together on the same chromosome.

The following is a linkage map. of four genes on a chromosome. Between which 2 genes would you expect the lowest frequency of recombination?

W and E

A girl with Down syndrome carries 3 copies of chromosome 21. The presence of 3 chromosomes is most likely caused by:

A defect in meiosis in one of her parents (nondisjunction)

2n

diploid

2n+1

aneuploid

n

haploid

Eukaryotic chromosomes are composed of a complex 60% protein and 40% DNA. This complex is refried to as

Chromatin

The protein cycle when the cell us growing and does not contain a replicated genome is reffferd to as

G1

What is the sequence of events in a typical eukaryotic cell cycle

G1 to S to G2 to mitosis to cytokinesis

A somatic cell from a corn plant normally contains 20 chromosomes. How many sister chromatids would that cell contain during the G2 of the cell cycle?

40

The mitotic spindle is a micro tubular structure that is involved in

separation of sister chromatids

The stage of mitosis characterized by the physical separation of sister chromatids is called

anaphase

Animal cells typically achieve cytokinesis by

Forming a cleavage furrow that. pinches. a cell in two

Some cells have several nuclei per cell. How could such multinucleated cells be explained?

The cell underwent repeated mitosis, but cytokinesis did not occur

...Is a process of nuclear division which reduces the number of chromosomes per cell from 2 sets to 1 set

meiosis

You are studying meiosis in an organism where 2n=24. How many chromosomes will each nucleus have after meiosis II is complete?

12

You inherited two copies of chromosome #8 from your parents (one from your mother, and one from your father). We refer to these paired

chromosomes as "homologous chromosomes". Which of the following is

true of homologous chromosomes?

they contain genes for the same traits

Which of the following happens at the conclusion of meiosis I

Homologous chromosomes of a pair are separated from each other

After telophase I of meiosis the chromosomal makeup of each daughter cell is

haploid and the chromosomes are each composed of 2 chromatids

Homologous chromosomes pair along their length during prophase 1 of meiosis. While two homologous are paired genetic exchange may occur between them in a process called

crossing over

Which best describes the process of independent assortment?

The way on pair of homologous line up along the metaphase plate does not affect how any. other pair lines up

Compared to asexual reproduction, the main advantage of sexual reproduction is that it

increases the genetic diversity of the offspring

During his experiments, Mendel referred to the trait the t was exposed in the F1 or first filial generation as

dominant

It was important that Mendel examined not just the F1 generation in his breeding experiments, but the F2 generation as well, because

Parental traits that were not observed in the F1 generation reappeared in the F2 generation

If fertilization involves two gametes that contain different alleles of a given generation, the resulting offspring is

Heterozygous

In certain plants, round seeds are completely dominant to wrinkled seeds. If a heterozygous plant is crossed with a homozygous round seeded plant what is the probability that the offspring will produce round seeds ?

1

In cattle "roan" coat color ( mixed red & and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rrr) homozygotes. Which of the following crosses would produce offspring int he ratio of 1:1 (roan:white)?

White x Roan

A black guinea pug crossed with an albino guinea pig produced twelve black offspring. When the albino was crossed with a second black animal sin black and six albinos were produced. What is the best explanation for this genetic situation?

Albino is recessive; black is completely dominant

True-breeding red roses crossed with true breeding white roses. All offspring red. This is an example of:

Complete dominance

Let R= red pigment and r= no pigment. In carnations, RR offspring make a lot of red pigment, rr offspring make no pigment and Rr offspring make a small amount of red pigment, thus appearing pink. Pink carnations are therefore an example of

Incomplete dominance

Height is a trait that shows continuous variation in humans. In pea plants, on the other hand, the tall allele is dominant over the short allele and there are no intermediate heights. What is the best explanation for this difference?

Height is a polygenic trait in humans

Sometimes one gene pair will interfere with the expression of a second gene pair in a interaction. called

Epistasis

Two carriers of a recessive allele are going to have a baby. What is the chance of them having a child that shows the normal (recesseive) phenotype?

1/4

Mendel's observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division?

Anaphase I of meisosis

In Thomas Hunt Morgan's experiments the white eye allele in fruit flies was shown to be

located on the X chromosome

Males are more often affected by the sex-linked traits than females because:

Males have only one copy of the X chromosome

A female who carries one particular allele of an X-linked gene will pass it on to

half of her daughters and sons

Allele pairs are most likely to assort independently of one another when

they are on different chromosomes

Recombination comes occurs between linked genes because

crossovers between these genes result in chromosomal exchange

The following linkage is a map of four genes on a chromosome. Between which 2 genes would you expect the lowest frequency of combination?

R and I

Occasionally chromosomes fail to separate during meiosis, leading to daughter cells that have an an abnormal number of chromosomes. This phenomenon is called

nondisjunction