merged 5

Two chromosomes in a nucleus that carry genes controlling the same inherited characteristics are___.

Homologous chromosomes.

Mitosis and cytokinesis result in the formation of _____; meiosis and cytokinesis result in the formation of _____.

2 diploid cells.... 4 haploid cells

At the end of telophase I of meiosis, as cytokinesis occurs, there are _____.

2 haploid cells

The function of meiosis is to make___.

4 cells with a haploid number of chromosomes.

What is the typical result when a diploid cell undergoes meiosis?

4 haploid cells

-Heterozygotes

= blood cholesterol levels about twice normal.

-Homozygotes

= five times the normal amount of blood cholesterol (may have heart attacks as early as age 2.)

Cancer is not usually inherited because A) the chromosomal changes in cancer are usually confined to somatic cells. B) people with cancer usually die before reproducing. C) cancer typically causes disruptions of meiosis. D) the causes of cancer are not usually genetic. E) the cancerous cells usually interfere with the ability to produce gametes.

A

How many generations does it take to develop a new plant species by nondisjunction? A) one B) two C) ten D) twenty E) fifty

A

Independent orientation of chromosomes at metaphase I and random fertilization are most like A) shuffling cards and dealing out hands of poker. B) cutting up a pie into eight even-sized slices. C) alphabetizing files in a filing cabinet. D) pairing up similar socks after washing your clothes. E) stringing beads onto a string to make a necklace.

A

Two chromosomes in a nucleus that carry loci for the same traits in the same positions on the chromosome but specify different versions of some traits constitute a pair of A) homologous chromosomes. B) heterologous chromosomes. C) complementary chromosomes. D) polyploid chromosomes. E) parallel chromosomes.

A

Which of the following variations of the sentence "Where is the cat" is most like a chromosomal deletion? A) Where is cat? B) Where is the the cat? C) Where the is cat? D) Where is cat the the cat? E) Where is is is is the cat?

A

Pedigree

A chart or "family tree" that tracks which members of a family have a particular trait

Sex-linked gene

A gene located on a sex chromosome; most sex-linked genes are found on the X chromosome.

In a diploid cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing _____ chromosomes. A) 5 B) 10 C) 20 D) 40 E) 0

A) 5

Which of the following occurs during anaphase I? A) Homologs separate and migrate toward opposite poles. B) Sister chromatids separate and migrate toward opposite poles. C) Nuclei re-form. D) Chromosomes line up in one plane. E) The cell is haploid.

A) Homologs separate and migrate toward opposite poles.

In sexually reproducing species, the chromosome number remains stable over time because _____ and _____ always alternate. A) meiosis ... fertilization B) meiosis ... mitosis C) mitosis ... fertilization D) meiosis ... interphase E) meiosis I ... meiosis II

A) meiosis ... fertilization

The synaptonemal complex _____. A) physically connects homologous chromosomes during prophase I B) physically connects homologous chromosomes during mitosis C) is broken down by enzymes during anaphase II D) is another name for chiasmata E) is formed by a protein called cohesin

A) physically connects homologous chromosomes during prophase I

What is a locus? A) the precise location of a gene on a chromosome B) a structure that appears during prophase I and consists of two paired genes C) the precise DNA sequence of a gene D) a type of spore made only by fungi E) a cell with two chromosome sets

A) the precise location of a gene on a chromosome

Need to know!

Many animals, including all mammals, have a pair of sex chromosomes, designated X and Y, that determine an individual's sex. -XY individuals are males. -XX individuals are females. Human males and females both have 44 autosomes (chromosomes other than sex chromosomes).

A pair of male human sex chromosomes is most like A) a pair of blue jeans. B) a bride and groom. C) a knife, fork, and spoon. D) identical twins. E) the letters of the alphabet.

B

Both mitosis and meiosis are preceded by A) prometaphase. B) interphase. C) prophase. D) telophase. E) anaphase.

B

During which stage of meiosis does synapsis and the formation of tetrads occur? A) interphase I B) prophase I C) interphase II D) prophase II E) metaphase I

B

If a chromosome fragment breaks off and then reattaches to the original chromosome, but in the reverse direction, the resulting chromosomal abnormality is called a(n) A) deletion. B) inversion. C) translocation. D) nondisjunction. E) reciprocal translocation.

B

Karyotyping A) shows chromosomes as they appear in metaphase of meiosis II. B) can reveal alterations in chromosome number. C) examines points of crossing over. D) reveals the results of independent orientation of chromosomes during meiosis I. E) reveals the presence of cancerous genes.

B

Which of the following options correctly describes the behavior of a tetrad during anaphase I of meiosis? A) It goes intact to one pole of the dividing cell. B) It splits into two pairs of sister chromatids, and one pair goes to each pole of the dividing cell. C) It splits into two pairs of homologous, nonsister chromatids, and one pair goes to each pole of the dividing cell. D) It splits into four chromosomes, which distribute in random pairs to the two poles of the dividing cell. E) It splits into four chromosomes, which distribute in sister-chromosome pairs to the two poles of the dividing cell.

B

Which of the following statements about nondisjunction is false? A) Nondisjunction in meiosis can affect autosomes and sex chromosomes. B) In mammals, extra copies of the Y chromosome are typically inactivated. C) The absence of a Y chromosome results in "femaleness." D) In general, a single Y chromosome is enough to produce "maleness." E) Women with a single X chromosome have Turner syndrome and are sterile.

B

Which of the following statements regarding mitosis and meiosis is false? A) Mitosis provides for growth and tissue repair. B) Meiosis provides for asexual reproduction. C) In mitosis, the chromosomes replicate only once in the preceding interphase. D) In meiosis, the chromosomes replicate only once in the preceding interphase. E) All the events unique to meiosis occur during meiosis I.

B

In a diploid set of chromosomes, one member of each pair of homologous chromosomes is derived from the father (paternal), and the other comes from the mother (maternal). If 2n = 6, what is the probability of obtaining a gamete in which all the chromosomes are paternal ones? A) 1/4 B) 1/8 C) 1/16 D) 1/32 E) The answer cannot be determined from these data.

B) 1/8

How many pairs of autosomes do humans have? A) 23 B) 22 C) 2 D) 1 E) It depends on the sex of the individual.

B) 22

Regarding the role of cohesin protein in maintaining cohesion between sister chromatids, which of the following statements is false? A) During meiosis I, cohesion holds sister chromatids together along their lengths as chiasmata form between homologs. B) During meiosis II, cohesion holds sister chromatids along their lengths as the second meiotic spindle forms. C) Cleavage of cohesins between sister chromatid arms at anaphase I allows homologs to separate. D) The first and second listed responses are false. E) The second and third listed responses are false. F) None of the listed responses is false.

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

Which of the following occurs during anaphase II? A) Homologs separate and migrate toward opposite poles. B) Sister chromatids separate and migrate toward opposite poles. C) Nuclei re-form. D) Chromosomes line up in one plane. E) The synaptonemal complex disappears.

B) Sister chromatids separate and migrate toward opposite poles.

Which event occurs only during prophase I of the first meiotic division? A) Homologous chromosomes line up at the center of the cell. B) Synapsis of homologous pairs occurs. C) The nuclear membrane breaks down. D) Replication of DNA takes place. E) A spindle of microtubules forms.

B) Synapsis of homologous pairs occurs.

The major contribution of sex to evolution is that _____. A) it is the only mechanism for species to reproduce B) it provides a method to increase genetic variation C) it provides a way in which somatic mutations can be inherited D) The first and second listed responses are correct. E) The second and third listed responses are correct.

B) it provides a method to increase genetic variation

Synapsis occurs during _____. A) anaphase I B) prophase I C) cytokinesis D) prophase II E) metaphase I

B) prophase I

Independent orientation of chromosomes at metaphase I results in an increase in the number of A) gametes. B) homologous chromosomes. C) possible combinations of characteristics. D) sex chromosomes. E) points of crossing over.

C

Mr. and Mrs. Smith have three sons in elementary school. Two of their children are progressing normally, but their last son, Charles, has been much slower than his siblings at developing speech and language skills. His parents are concerned that he has a learning disability and decide to investigate further. Since some learning disabilities can be genetically based, their pediatrician recommends a chromosomal analysis. The results show that Charles has a trisomy of the sex chromosomes, diagnosed as XYY, which is caused by nondisjunction in the formation of the father's sperm. The nondisjunction resulted in an extra copy of the Y chromosome. The extra copy was passed on to Charles during fertilization. Most often, this chromosomal change causes no unusual physical features or medical problems, but those with trisomy of the sex chromosomes do have a higher than normal risk of delays in learning development. 1) During which stage of meiosis must this nondisjunction have occurred? A) anaphase I B) metaphase I C) metaphase II D) anaphase II E) prophase II

C

Which of the following statements regarding genetic diversity is false? A) Genetic diversity is enhanced by random fertilization. B) Genetic diversity is enhanced by independent orientation of chromosomes at metaphase I. C) Genetic diversity is enhanced by mitosis of somatic cells. D) Genetic diversity is enhanced by crossing over during prophase I of meiosis. E) Genetic diversity is enhanced by random mutations of the DNA.

C

Which of the following statements regarding mitosis and meiosis is false? A) Meiosis only occurs in the ovaries and testes. B) All sexual life cycles involve an alternation of diploid and haploid stages. C) Mitosis produces daughter cells with half the number of chromosomes as the parent cell. D) A normal human zygote has 46 chromosomes. E) A haploid cell has half the chromosomes of a diploid cell.

C

Which of the following types of organisms commonly demonstrates polyploidy? A) mammals B) reptiles C) flowering plants D) amphibians E) fish

C

In humans, the haploid number of chromosomes is 23. Independent assortment has the possibility of producing _____ different types of gametes. A) 23^2 B) 1 million C) 2^23 D) 24 E) 100,000

C) 2^23

The egg (ovum) of a rabbit contains 22 chromosomes. How many chromosomes are in the somatic (body) cells of a rabbit? A) 11 B) 22 C) 44 D) 88 E) 132

C) 44

Which phase of meiosis does synapsis and crossing over occur?

Prophase I

What is the key difference between meiosis and mitosis?

Synapsis occurs

Codominant

The IAand IB alleles are codominant, meaning that both alleles are expressed in heterozygous individuals (IAIB) who have type AB blood.

Which of the following statements reflects an advantage that sexual reproduction likely provides over asexual reproduction? A) In terms of energetic costs, sexual reproduction is a cheaper strategy than asexual reproduction for generating genetic variation in a population. B) Although sexual and asexual reproduction both offer opportunities for increasing genetic variation, sexual reproduction is comparatively lower in its energetic costs to the organism. C) Although energetically more costly than asexual reproduction, sexual reproduction leads to different combinations of alleles that could provide adaptability in a changing environment. D) Sexual reproduction maintains the same combination of alleles and does not run the risk of losing successful combination of alleles as is observed to occur in asexually reproducing organisms. E) Although both reproductive strategies perpetuate the same combination of alleles within individuals in a population, sexual reproduction is energetically less costly than asexual reproduction.

C) Although energetically more costly than asexual reproduction, sexual reproduction leads to different combinations of alleles that could provide adaptability in a changing environment.

Fertilization produces _____. A) a haploid zygote in some life cycles and a diploid zygote in others B) a haploid zygote C) a diploid zygote D) a diploid zygote, except during the gametophyte stage of alternation of generations E) a multicellular haploid organism in a life cycle with an alternation of generations

C) a diploid zygote

Sister chromatids _____. A) are only involved in mitosis B) are pairs of chromosomes, one of which comes from the father and one of which comes from the mother C) are identical copies of each other formed during DNA synthesis D) have the same gene loci but may have different alleles of some genes E) are only involved in meiosis

C) are identical copies of each other formed during DNA synthesis

In a male mammal, every cell that undergoes meiosis gives rise to _____ sperm. A) one B) two C) four D) no set number E) zero

C) four

Spores and gametes are different in that _____. A) gametes never resemble spores morphologically B) gametes are always haploid whereas spores are diploid C) gametes can fuse to form a zygote, but spores can develop into independent organisms without first forming a zygote D) only the formation of gametes contributes to genetic variation E) gametes are derived directly from sporophytes to form gametophytes

C) gametes can fuse to form a zygote, but spores can develop into independent organisms without first forming a zygote

When we say that an organism is haploid, we mean that _____. A) its cells each have one chromosome B) it has one half of a chromosome C) its cells have a single set of chromosomes D) its cells have two sets of chromosomes E) its cells have half of one set of chromosomes

C) its cells have a single set of chromosomes

Which of the following results in cells that contain half the parental chromosome number? A) cytokinesis B) mitosis C) meiosis D) interphase E) metaphase

C) meiosis

Which of the following answers is not involved nor an outcome of crossing over? A) The DNA in two nonsister chromatids is broken by specific proteins at exact points. B) Chiasmata indicate where crossing over is occurring between homologs. C) the random alignment of homologous pairs of chromosome at metaphase I D) formation of chromosomes containing paternal and maternal alleles E) All of the listed responses pertain to the process of crossing over.

C) the random alignment of homologous pairs of chromosome at metaphase I

During meiosis I, homologous chromosomes form a tetrad. What does this accomplish?

Crossing over can occur, creating new combinations of chromosomes through their independent alignment across the metaphase plate

A karyotype is most like A) a map showing the hidden location of buried treasure. B) a movie showing the stages of the reproductive cycle of a beetle. C) a necklace formed by stringing beads onto a string. D) photographs of every couple at a high school prom. E) the answer key to a multiple-choice exam.

D

Nondisjunction occurs when A) a portion of a chromosome breaks off and is lost. B) chromosomes replicate too many times. C) two chromosomes fuse into one. D) members of a chromosome pair fail to separate. E) an entire pair of chromosomes is lost during meiosis I.

D

Which of the following statements is false? A) A typical body cell is called a somatic cell. B) Gametes are haploid cells. C) Somatic cells are diploid. D) Gametes are made by mitosis. E) A zygote is a fertilized egg.

D

Which of the following statements regarding the differences between mitosis and meiosis is false? A) In meiosis four daughter cells are produced, whereas in mitosis two daughter cells are produced. B) Cells produced by mitosis are diploid, whereas cells produced by meiosis are haploid. C) In mitosis cytokinesis occurs once, whereas in meiosis cytokinesis occurs twice. D) Crossing over is a phenomenon that creates genetic diversity during mitosis. E) Mitosis, but not meiosis, occurs in somatic cells.

D

Ignoring crossover, how many kinds of gametes can be produced by an organism with a diploid number of 8? A) 2 B) 4 C) 8 D) 16 E) 32

D) 16

A karyotype is _____. A) the physical traits a person has B) a method of identifying crossover events C) all the possible gametes a person could produce D) a photograph of all of an individual's chromosomes E) a list of all the genes a person carries

D) a photograph of all of an individual's chromosomes

Nearly all life cycles have both haploid and diploid phases. Usually, the transition from haploid to diploid takes place _____. A) during crossing over in meiosis B) when DNA is replicated during the S phase of the cell cycle C) when mitotic cytokinesis occurs D) at fertilization, when gametes fuse E) during gastrulation

D) at fertilization, when gametes fuse

Regions of chromosomes where nonsister chromatids cross over are called _____. A) inversions B) homologs C) kinetochores D) chiasmata E) tetrads

D) chiasmata

What is the result when a diploid cell undergoes meiosis? A) two diploid cells B) two haploid cells C) four diploid cells D) four haploid cells E) two haploid cells and two diploid cells

D) four haploid cells

Humans have 46 chromosomes. This number of chromosomes will be found in _____. A) all cells in anaphase of mitosis B) all the egg and sperm cells C) all gamete-producing cells after meiosis I D) liver cells E) all the cells of the body

D) liver cells

Which of the following is a function of mitosis in humans? A) production of eggs B) production of sperm C) decreasing the number of chromosomes D) multiplication of body cells E) increasing genetic variability

D) multiplication of body cells

Unless the chromosomes were stained to show band patterns, a karyotype would be least likely to show which of the following? A) an extra chromosome B) a large part of a chromosome duplicated C) a missing chromosome D) part of a chromosome turned around E) the attachment of a large part of a chromosome to another chromosome

D) part of a chromosome turned around

Which of the following contributes to genetic variation in sexually reproducing species? A) crossing over, internal fertilization, independent assortment B) independent assortment, spindle formation, random fertilization C) random fertilization, DNA synthesis, independent assortment D) random fertilization, independent assortment, crossing over E) internal fertilization, spindle formation, crossing over

D) random fertilization, independent assortment, crossing over

Although _____ is nearly universal among animals, bdelloid rotifers _____. A) asexual production ... have achieved great diversity by using sexual reproduction B) sexual reproduction ... reproduce asexually and achieve genetic diversity by mutations alone C) sexual production ... reproduce asexually because they inhabit very stable environments and the production of gametes would be an inefficient use of energy D) sexual reproduction ... reproduce asexually but can increase genetic variation present in a population by means of the uptake of DNA from other rotifers

D) sexual reproduction ... reproduce asexually but can increase genetic variation present in a population by means of the uptake of DNA from other rotifers

How many genes are present in the human genome? A) 23 B) 46 C) hundreds D) tens of thousands E) a virtually infinite number

D) tens of thousands

Sexual and asexual reproduction are alike in that _____. A) they both give rise to genetically distinct offspring B) they both involve two parents C) they both require meiosis to complete the reproductive cycle D) they can both occur in multicellular organisms E) in both cases, every parent transmits all of its genes to its progeny

D) they can both occur in multicellular organisms

What is the function of meiosis? A) to make exact copies of the parent cell B) to make one cell with twice the number of chromosomes as the parent pairs C) to make four cells with the same chromosome number as the parent D) to make cells with a haploid (half that of the parents) number of chromosomes E) to make diploid spores

D) to make cells with a haploid (half that of the parents) number of chromosomes

Somatic cells in humans contain _____ set(s) of chromosomes and are therefore termed _____. A) one ... diploid B) two ... haploid C) one ... haploid D) two ... diploid E) three ... triploid

D) two ... diploid

If Charles gets married and starts a family, which of the following chromosomal abnormalities might be found in his children? A) XY B) XX C) XYY D) XO E) XXY

E

Which of the following statements regarding Down syndrome is false? A) Trisomy 21 usually leads to Down syndrome. B) A human embryo with an abnormal number of chromosomes is usually spontaneously aborted. C) Down syndrome is the most common serious birth defect in the United States. D) People with Down syndrome usually have a life span much shorter than normal. E) Women with Down syndrome cannot reproduce.

E

Which, if any, of the following statements is true? A) Diploid cells can divide by mitosis. B) Diploid cells can divide by meiosis. C) Haploid cells can divide by mitosis. D) Haploid cells cannot divide by meiosis. E) All of the above responses are correct.

E) All of the above responses are correct. (Diploid cells can divide by mitosis; Diploid cells can divide by meiosis; Haploid cells can divide by mitosis; Haploid cells cannot divide by meiosis)

A clone is the product of _____. A) asexual reproduction B) sexual reproduction C) mitosis D) meiosis E) The first and third listed responses are correct. F) The second and fourth listed responses are correct.

E) The first and third listed responses are correct.(asexual reproduction and mitosis)

The diploid number of chromosomes in a certain animal is 8 (2n = 8). How do the four pairs of homologous chromosomes align and separate during meiosis? A) All of the maternal chromosomes always move to one pole, and all the paternal chromosomes always move to the other pole. B) All 16 chromatids move together. C) Exactly two maternal and two paternal chromosomes always move to each of the two poles. D) The first to move influences all the others. E) They align and assort independently to form any of 16 different combinations.

E) They align and assort independently to form any of 16 different combinations.

Which function makes meiosis lengthier and more complex than mitosis? A) decreasing the chromosome number to haploid B) introducing genetic variation among the daughter cells C) ensuring that each daughter cell gets a single, complete set of chromosomes D) undergoing two rounds of cytokinesis E) all of the above

E) all of the above (decreasing the chromosome number to haploid; introducing genetic variation among the daughter cells; ensuring that each daughter cell gets a single, complete set of chromosomes; undergoing two rounds of cytokinesis)

Which of the following is part of the life cycle called alternation of generations? A) multicellular haploid stage (gametophyte) B) multicellular diploid stage (sporophyte) C) zygote D) spores E) all of the above

E) all of the above (multicellular haploid stage (gametophyte); multicellular diploid stage (sporophyte); zygote; spores)

The sexual cycle of the multicellular algal genus Fucus involves _____. A) mitosis only B) both mitosis and meiosis but not fertilization C) both mitosis and fertilization but not meiosis D) only meiosis and fertilization E) mitosis, meiosis, and fertilization

E) mitosis, meiosis, and fertilization

Crossing over occurs during _____. A) cytokinesis B) metaphase I C) prophase II D) metaphase II E) prophase I

E) prophase I

At the end of telophase I of meiosis and the first cytokinesis, there are _____. A) four haploid cells B) two diploid cells C) four diploid cells D) one haploid ovum and three polar bodies E) two haploid cells

E) two haploid cells

There are three alleles, so there are six possible genotypes: name them?

-IAIA and IAi people have type A blood, -IBIB and IBi people have type B. -Recessive homozygotes (ii) have type O blood with neither carbohydrate. -People of genotype IAIB make both carbohydrates

Most genes can be found in more than 2 forms ("multiple alleles") The ABO blood groups in humans involve three alleles of a single gene.

-Various combinations of these three alleles produce four phenotypes. Therefore, a person's blood type may be A, B, AB, or O. -These letters refer to two carbohydrates, designated A and B, that may be found on the surface of red blood cells.

Need to know !

-genes are responsible for inherited traits -genes retain their individual identities generation after generation.

What are some human disorders caused by dominant alleles ?

Ex: achondroplasia: form of dwarfism in which the head and torso develop normally but the arms and legs are short

The M phase of mitosis and M phase of meiosis both occur after interphase. However, the two processes differ in the arrangement and behavior of their chromosomes. How?

The pairing up of homologous chromosomes and crossing over only occur during meiosis.

Which of the following is a normal female?

XX

A example of a cell that is 2n is....

a somatic cell

Crossing over is important because it causes

allows the exchange of genes between homologus chromosomes.

Linked genes

are located near each other on the same chromosome and tend to travel together during meiosis and fertilization.

Most people who have recessive disorders are born to normal parents who are heterozygotes:

carriers

Hypercholesterolemia

characterized by dangerously high levels of cholesterol in the blood.

The diploid phase of human life begins with

fertilization

Without crossing over

genetic recombination would not occur

In anaphase I__

homologus chromosomes move toward opposite poles

During anaphase I ____.

homolugues seperate and migrate toward opposite poles.

Incomplete dominance

hybrids have an appearance between the parent phenotypes. RR = red rr = white Rr = pink *R is not completety dominant

Both mitosis and meiosis are preceded by

interphase

When we say that an organism is a haploid, we mean that

its cells each have one set of chromosomes

Varation occurs when chromosomes are shuffled in ____.

meiosis

At a critical point in meiosis, the chromosomes do not replicate. This occurs between _____.

metaphase I and anaphase I

Dominant traits are not what ?

necessarily "normal" or more common than recessive phenotype. - dominance means that a heterozygous genotype results in the dominant phenotype.

Independent oreintation of chromosomes at metaphase I results in an increase in the number of ___

possible combination of characteristics

Synapsis occurs during

prophase I

crossing over occurs during___?

prophase I

Most genetic mutations that cause medical disorders are?

recessive

In meisosis II

sister chromatids are seperated

During anaphase II _____.

sister chromatids seperate and migrate toward opposite poles.

Chromosome Theory of Inheritance

states that genes are located at specific positions (loci) on chromosomes and the behavior of chromosomes during meiosis and fertilization accounts for inheritance patterns.

Polygenic inheritance

the additive effects of two or more genes on a single phenotypic character

Epigenetic inheritance; give an example

the transmission of traits by mechanisms not directly involving DNA sequence. Ex: components of chromosomes can be chemically modified - add/remove chemical groups on the DNA and/or protein components of chromosomes.

Pleiotropy

when one gene influences several characters. Ex: Sickle-cell disease: results in abnormal hemoglobin proteins, and causes disk-shaped red blood cells to deform into a sickle shape with jagged edges.