Biology 1, Chapter 13

Ignoring crossover, how many kinds of gametes can be produced by an organism with a diploid number of 8?

16

The egg (ovum) of a rabbit contains 22 chromosomes. How many chromosomes are in the somatic (body) cells of a rabbit?

44

__________ are a group of genetically identical individuals produced by a process called __________.

Clones; asexual reproduction

What is the result when a diploid cell undergoes meiosis?

Four haploid cells

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

Homologous chromosomes of a pair are separated from each other.

Which life cycle stage is found in plants but not animals?

Multicellular haploid

Which of the following is a function of mitosis in humans?

Multiplication of body cells

How is natural selection related to sexual reproduction as opposed to asexual reproduction?

Sexual reproduction results in many new gene combinations, some of which will lead to differential reproduction.

Sister chromatids differ from nonsister chromatids in that sister chromatids __________.

are products of the S phase of the cell cycle and are two copies of one chromosome

A clone is the product of __________.

asexual reproduction and mitosis

Somatic cells in humans differs from gametes in that human somatic cells __________.

contain two sets of each of the 23 chromosome types

Darwin realized the importance of heritable variation to evolution __________.

even though he never read any of Gregor Mendel's work

A life cycle in which the only multicellular form is haploid is most typical of __________.

fungi

Allelic variation is an important source of __________ in a population.

genetic variation

A pair of genetic structures carrying genes that control the same inherited characters are called __________.

homologous chromosomes

Characteristic of the bdelloid rotifer is that it __________.

is an example of an animal that has not reproduced sexually in 40 million years

The major contribution of sex to evolution is that __________.

it provides a method to increase genetic variation

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

meiosis I

In meiosis, __________ of __________ cross over and form __________.

nonsister chromatids; homologous pairs; chiasmata

Genetic diversity requires __________.

sexual reproduction, independent assortment, crossing over between nonsister chromatids of homologous chromosomes, and random fertilization

What is crossing over?

the exchange of homologous portions of nonsister chromatids

Independent assortment of chromosomes is a result of _____.

the random way each pair of homologous chromosomes lines up at the metaphase plate during meiosis I

Somatic cells in humans contain __________ set(s) of chromosomes and are therefore termed __________.

two; diploid

At the end of mitosis, __________ daughter cells that are genetically __________ are formed, while at the end of meiosis, __________ daughter cells that are genetically __________ are formed.

two; identical; four; distinct

Regarding the role of cohesin protein in maintaining cohesion between sister chromatids, which of the following statements is false?

During meiosis II, cohesion holds sister chromatids together along their lengths as the second meiotic spindle forms.

How are sister chromatids and homologous chromosomes different from each other?

Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication.

Which of the following occurs in meiosis, but not mitosis?

Homologous chromosomes separate.

Which diagram represents anaphase I of meiosis? #5

I

Unless the chromosomes were stained to show band patterns, a karyotype would be least likely to show which of the following?

Part of a chromosome turned around.

What is a major difference between mitosis and meiosis I in a diploid organism?

Sister chromatids separate in mitosis, while homologous pairs of chromosomes separate in meiosis I.

How many genes are present in the human genome?

Tens of thousands

What is a locus?

The precise location of a gene on a chromosome.

Which of the following statements about homologous chromosomes is correct?

They have genes for the same trait at the same loci

The life cycle called __________ in plants has two multicellular stages: the __________ and the __________.

alternation of generations; haploid gametophyte; diploid sporophyte

Centromeres split and sister chromatids migrate to opposite poles in meiosis _____.

anaphase II

Somatic cells in animals differ from gametes in that somatic cells __________.

are all of the cells of the body except for the gametes and their precursors

Regardless of whether an organism is an animal, a plant, a fungus, or an algal cell, all zygotes are __________ and are formed during the __________ of two __________ gametes.

diploid; fertilization; haploid

Homologous pairs of chromosomes align opposite of each other at the equator of a cell during _____.

meiosis metaphase I

The process called __________ reduces the chromosome number by __________.

meiosis; two consecutive cell divisions

The zipper-like complex that forms in meiosis occurs during __________ and is called the __________.

prophase I; synaptonemal complex