Bio Chapter 10

The synaptonemal complex

physically connects homologous chromosomes during prophase I

In alternation of generations, what is the diploid stage of a plant that follows fertilization called?

sporophyte

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.

Sort each process into the appropriate bin according to whether it contributes to heredity only, genetic variation only, or both. (Note that a bin may be left empty.)

All are both heridatary and genetic variation - fertilization, crossing over, meta0hase 1 to anaphase 1, metaphase 2 to anaphase 2, dna replication

Based on this data, how much DNA is present in a gamete of Saccharomyces cerevisiae?

12 fg

In human gamete production there is an average of _____ crossover events per chromosome pair.

2-3

How many femtograms of DNA are present in a cell at the end of meiosis I?

24 fg

Which of the following is included in alternation of generations?

All of the above : Zygote, spores, multicellular diploid stage (sporophyte), multicellular haploid stage (gametophyte)

Choose the correct makeup of a haploid set and the correct makeup of a diploid set.

All red and blue chromosomes together make up a diploid set., The chromosomes of one colour make up a haploid set.

During mitosis or meiosis, sister chromatids are held together by proteins referred to as cohesins. Such molecules must have which of the following properties?

They must be removed before sister chromatids or homologous chromosomes can separate.

For a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes?

approximately 8,4 million

Genetic variation occurs when chromosomes are shuffled in fertilization and what other process?

meiosis

Which of the following types of organisms has both diploid and haploid forms that exist as separate individuals?

some algae

At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.

telophase I

At the end of _____ and cytokinesis there are four haploid cells.

telophase II

How many genes are present in the human genome?

tens of thousands

Complete the diagram to show the life cycle of a typical animal.

yes

Which of the following is true of an organism that has a chromosome number of 2n = 16?

Each cell has eight homologous pairs of chromosomes.

Which of the following statements about humans is true?

The 23rd pair, the sex chromosomes, determines whether the person is female (XX) or male (XY).

How many femtograms of DNA are present in a cell at the end of meiosis II?

12 fg

How many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8 (2n = 8)?

16 (The number of possible combinations when chromosomes sort independently during meiosis is 2n, where n is the haploid number of the organism. A cell with a diploid number of 8 would have a haploid, or n number, of 4. The possible number of combinations of chromosomes would therefore be 16.)

Human somatic cells contain __________ set(s) of chromosomes and are therefore termed _

2, diploid

How many pairs of autosomes do humans have?

22 pairs of autosomes

Normal human gametes carry _____ chromosomes.

23. This is the number of chromosomes in a single set of human chromosomes.

Most of the yeast cells in the culture were in G1 of the cell cycle before being moved to the nutrient-poor medium to induce meiosis. A graphical version of the data (similar to the one you just made) is shown (Figure 1). How many femtograms of DNA are there in a yeast cell in G1? Estimate this value from the data in the graph.

24 fg

If the DNA content of a diploid cell in the G1 phase of the cell cycle is represented by x, then the DNA content of the same cell at metaphase of meiosis I would be _

2x

In a male mammal, every germ cell that undergoes meiosis in the production of gametes gives rise to __________ sperm.

4

If a horticulturist breeding plants known as gardenias succeeds in having a single plant with a particularly desirable set of traits, which of the following processes would be her most probable and efficient route to establishing a line of such plants with that particular set of traits?

Clone the plant asexually to produce an identical one.

You have isolated DNA from three different cell types of an organism, determined the relative DNA content for each type, and plotted the results on the graph shown in the figure above. Which sample(s) of DNA might be from a cell at the end of anaphase II of meiosis?

III

If a cell has completed the first meiotic division and is just beginning meiosis II, which of the following statements describes the genetic or chromosomal contents of this cell?

It has half the amount of DNA of the cell that began meiosis.

In a life cycle such as that shown in diagram II of the figure above, if the zygote's chromosome number is 10, which of the following will be true?

The sporophyte's chromosome number per cell is 10, and the gametophyte's is 5.

Look at the cell in the figure. Based on this figure, which of the following statements is true?

This cell is diploid.

Which phase of meiosis is represented in the figure above?

anaphase I

Sister chromatids are

are identical copies of each other formed during DNA synthesis

What variable's response to the independent variable was measured by the researchers, and what are the units for this variable?

average amount of DNA per cell, in femtograms

uring which process does independent assortment of chromosomes occur?

during meiosis I

Meiosis II typically produces _____ cells, each of which is _____

four ... haploid

After telophase II of meiosis, the chromosomal makeup of each daughter cell is

haploid, and the chromosomes are each composed of a single daughter chromosome.

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

haploid, and the chromosomes are each composed of two chromatids.

Use the data at left to make a line graph. To create the graph, first click on "add graph" and select the label "Amount of DNA per Cell Over Time." (For more help using the graphing tool, open the hint.)

https://snag.gy/tVkmTJ.jpg

In a human karyotype, chromosomes are arranged in 23 pairs. If we choose one of these pairs, such as pair 14, which of the following characteristics are most likely for the two chromosomes of the pair to have in common?

length, centromere position, staining pattern, and traits coded for by their genes

Homologous chromosomes move toward opposite poles of a dividing cell during

meiosis 1

Human gametes are produced by

meiosis : produces haploid gametes from a diploid parental cell

In a cell undergoing meiosis, if homologous chromosomes are aligned at the equator of the meiotic spindle, what process has occurred?

metaphase 1

A certain (hypothetical) organism is diploid, has either blue or orange wings as the consequence of one of its genes on chromosome 12, and has either long or short antennae as the result of a second gene on chromosome 19, as shown in the figure above. A certain female's number 12 chromosomes both have the blue gene and number 19 chromosomes both have the long gene. As cells in her ovaries undergo meiosis, her resulting eggs (ova) may have which of the following?

one chromosome 12 with one blue gene and one chromosome 19 with one long gene

If chiasmata can be seen in a cell under a microscope, which of the following meiotic processes must have occurred?

prophase 1

To see patterns in the data from a time-course experiment like this, it is helpful to plot the data on a line graph. But first, you must determine which variable should go on each axis of the graph. What variable did the researchers intentionally vary in the experiment, and what are the units for this variable? (This is the independent variable.)

time after induction, in hours

If the DNA content of a diploid cell in the G1 phase of the cell cycle is represented by x, then the DNA content of the same cell at metaphase of meiosis I would be 2x. If we continued to follow the cell lineage, the DNA content of a cell at metaphase of meiosis II would be __

x

In a cell undergoing meiosis, if centromeres of sister chromatids become disjoined and chromatids separate, what process has occurred?.

anaphase II

During _____ sister chromatids separate.

anaphase II Anaphase II is essentially the same as mitotic anaphase except that the cell is haploid.

Select Figure 2 in the drop-down menu (Figure 2). The graph with labels indicating the different phases of the meiotic cell cycle (MI = meiosis I; MII = meiosis II) is shown. Think carefully about the point on the graph where the line at the highest value begins to slope downward, indicated by the red arrow. What specific point of meiosis does this "corner" represent?

cytokinesis

Refer to the figure above. Which of the progression of events listed corresponds to the series of events that occurs in the life cycle of animals?

diploid multicellular organism, meiosis, fertilization, zygote, mitosis

Fertilization produces a

diploid zygote

Chromatids are separated from each other during which of the following processes?

during both mitosis and meiosis II

The two homologs of a pair move toward opposite poles of a dividing cell during ______.

meiosis I

In the life cycle of fungi and some protists, which of the following processes leads to the formation of gametes?

meiosis in the diploid zygote

In sexually reproducing species, the chromosome number remains stable over time because __________ and __________ always alternate.

meiosis; fertilization

Which phase of meiosis is represented in the figure above?

metaphase 2

Homologous pairs of chromosomes are lined up independently of other such pairs during

metaphase I

Identify the stage of meiosis shown.

metaphase I

A karyotype is a

picture of an individual's chromosomes arranged in a standardized way

What is crossing over?

the exchange of homologous portions of nonsister chromatids

What is a locus?

the precise location of a gene on a chromosome

Drag the labels to fill in the targets beneath each diagram of a cell. Note that the diagrams are in no particular order.

yes

Drag the labels to their appropriate targets to correctly identify the various chromosome structures. Labels can be used more than once.

yes

asexual reproduction

produces offspring genetically identical to the parent

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

44

What number and types of chromosomes are found in a human somatic cell?

44 autosomes and 2 sex chromosomes

Sort each daughter cell into the appropriate bin depending on which arrangement at metaphase I would create it.

yasss boo

Can you recognize the eight stages of meiosis based on the location and behavior of the chromosomes?

yes

If crossing over did not occur, which of the following statements about meiosis would be true? Select all that apply.

There would be less genetic variation among gametes.

Which of the following human cells contain 46 chromosomes?

liver cells

Meiosis I produces _____ cells, each of which is _____.

two ... haploid

The diagram shows a cell in meiosis. Drag the labels to their appropriate locations in the diagram.

kinetochore, centromere, sister chromatid, gene loci, chiasma, sister chromatid cohesion, homologous pair, chromosome, alleles of the F gene, nonsister chromatids, kinetochore

Crossing over, resulting in an increase in genetic variation, occurs between _____

nonsister chromatids of homologous chromosomes

Which of the following is the smallest unit of life that would contain a complete copy of the entire human genome?

one human somatic cell

Crossing over occurs during __________.

prophase 1

During _____ a spindle forms in a haploid cell.

prophase II Prophase II is essentially the same as mitotic prophase except that the cells are haploid.

Which processes lead to most genetic variation in sexually reproducing organisms?

random fertilization, independent assortment of chromosomes in meiosis, crossing over

Which of these gametes contains one or more recombinant chromosomes?

B and C

Which of these gametes contain one or more recombinant chromosomes?

B,C,F, and G

Choose all possible combinations of these alleles in this person's gametes.

"freckles" and "blond hair" "freckles" and "black hair" "no freckles" and "black hair" "no freckles" and "blond hair"

The parent cell that enters meiosis is diploid, whereas the four daughter cells that result are haploid. Which statement correctly describes how cellular DNA content and ploidy levels change during meiosis I and meiosis II?

DNA content is halved in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II.

The two chromatids were formed by duplication of a chromosome.

Gametes (sperm and eggs), Spores

The diagram represents a meiotic cell. Assume that the freckles gene is at the locus marked F, and the hair-color gene is located at the locus marked H, both on the long chromosome. The person from whom this cell was taken has inherited different alleles for each gene ("freckles" and "black hair" from one parent and "no freckles" and "blond hair" from the other). Predict allele combinations in the cells resulting from this meiotic event. (It will help if you draw out the rest of meiosis and label the alleles by name.)

Two cells will be obtained after meiosis I. The first cell will bear "freckles" and "black hair" + "no freckles" and "black hair" alleles and the second will bear "no freckles" and "blond hair" + "freckles" and "blond hair" alleles.

In sexual reproduction independent______and crossing over during____together with random_____contribute to genetic variation in a population, which is the raw material for evolution by_______especially in changing environment.

assortment of chromosomes, meiosis I, fertilization, natural selection

Heritable variation is required for which of the following?

evolution

Specific traits are programmed by__and offspring inherit their__from each parent that leads to similarities in their appearance to one or the other parent. Humans reproduce___which ensures new combinations of__(and thus traits) in the offspring. Consequently, the offspring are not clones of their parents (which would be the case if humans reproduced__During meiosis___and the independent assortment of chromosomes produce many new combinations of alleles, and__brings together the__of individuals with different genetic backgrounds. Thus, via___independent assortment of chromosomes, and fertilization, sexual reproduction reshuffles alleles into fresh combinations each generation.

genes, genes, sexually, genes, asexually, crossing over, fertilization, gametes, crossing over

This cell must be undergoing ______ because ______ are associated with each other at the metaphase plate and chiasmata are present.

meiosis; homologous chromosomes

What diagnostic procedures can a karyotype be used for?

screening for defective or abnormal numbers of chromosomes in an individual

Drag the labels from the left to their correct locations in the concept map on the right.

yes

How many femtograms of DNA are present in a cell in G2?

48 fg

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?

1/8

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.

16

Which of these cells is (are) haploid?

After Meiosis I and Meiosis II (C &D) - Once meiosis I is completed, cells are haploid.

Two sister chromatids are joined at the centromere prior to meiosis. Which statement is correct?

Barring mutation, the two sister chromatids must be identical.

You have isolated DNA from three different cell types of an organism, determined the relative DNA content for each type, and plotted the results on the graph shown in the figure above. Which sample(s) of DNA might be from a germ cell arrested in prophase I of meiosis?

II

During _____ chromosomes align single file along the equator of a haploid cell.

Metaphase II is essentially the same as mitotic metaphase except that the cell is haploid.

Synapsis occurs during _____.

Prophase I

Which of the following occurs during anaphase II?

Sister chromatids separate and migrate toward opposite poles.

A human cell containing 22 autosomes and a Y chromosome is

a sperm

Spores and gametes differ in that

gametes must fuse to form a zygote and continue development, but each spore can develop into an independent multicellular organisms on its own

Which of the following statements regarding sexual life cycles is correct?

Sexual life cycles can produce both haploid and diploid cells at different stages.

When homologous chromosomes cross over, what is the result?

Specific proteins break the two strands of nonsister chromatids and re-join them.

Which of the following occurs during meiosis but not during mitosis?

Synapsis occurs.

Which event occurs only during prophase I of the first meiotic division?

Synapsis of homologous chromosomes occurs.

This chromosome has two chromatids, joined at the centromere. What process led to the formation of the two chromatids?

The two chromatids were formed by duplication of a chromosome.`

Homologous chromosomes migrate to opposite poles during

anaphase I During anaphase I sister chromatids remain attached at their centromeres, and homologous chromosomes move to opposite poles.

In a typical animal, mitosis produces ____________ while meiosis produces _____________.

two diploid daughter cells ... four haploid daughter cells

Given the fact that 1 fg of DNA = 9.78 ×× 105 base pairs (on average), you can convert the amount of DNA per cell to the length of DNA in numbers of base pairs. Millions of base pairs (Mb) is the standard unit for expressing genome size. Calculate the approximate number of base pairs of DNA in the haploid yeast genome.

12 Mb (12 x 106 base pairs )

Now that you have determined which variable goes on each axis, the graph can be constructed. An effective graph marks off the axes with just enough evenly spaced tick marks to accommodate the full set of data. Assuming that the x-axis tick marks will be separated by 1.0 units (0, 1.0, 2.0, and so on), what is the largest value that should appear on the x-axis?

14.0

Given the fact that 1 fg of DNA = 9.78 ×× 105 base pairs (on average), you can estimate the rate of DNA synthesis in Saccharomyces cerevisiae. Approximately how many base pairs per minute were synthesized during the S phase of these yeast cells?

200,000 (2.0 ×× 105) base pairs per minute

Scientists have produced a hybrid plant that was the result of the fertilization of gametes between one plant with a diploid number of 24 and another with a diploid number of 20. How many chromosomes would the diploid hybrid plant have?

22 chromosomes

In a diploid cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing __________ chromosomes.

5

Assuming that the y-axis tick marks will be separated by 5 units (0, 5, 10, and so on), what is the largest value that should appear on the y-axis?

55.0

Which of the following statements best describes the advantage that sexual reproduction likely provides over asexual reproduction?

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

A certain (hypothetical) organism is diploid, has either blue or orange wings as the consequence of one of its genes on chromosome 12, and has either long or short antennae as the result of a second gene on chromosome 19, as shown in the figure above. A female with a paternal set of one orange and one long gene chromosome and a maternal set composed of one blue and one short gene chromosome is expected to produce which of the following types of eggs after meiosis?

Each egg has a one-fourth chance of having blue long, blue short, orange long, or orange short combinations.

Refer to the life cycles illustrated in the figure above. Which of the life cycles is (are) typical for animals?

Fertilization - 2n (diploid) zygote - mitosis - 2n - meiosis - n out - n gametes - n going in

Refer to the life cycles illustrated in the figure above. Which of the life cycles is (are) typical for plants and some algae?

Fertilization - 2n zygote - mitosis- 2n - meiosis - n out - n spores/mitosis - big n - n mitosis - n going in

Which of the following statements correctly describes the differences between sexual and asexual reproduction?

In sexual reproduction, offspring vary genetically from their siblings and both parents.

What is the best evidence telling you whether this cell is diploid or haploid?

The cell is diploid because it contains two sets of chromosomes.

Which of the following contributes to genetic variation in sexually reproducing species?

independent assortment, crossing over, and random fertilization

A certain (hypothetical) organism is diploid, has either blue or orange wings as the consequence of one of its genes on chromosome 12, and has either long or short antennae as the result of a second gene on chromosome 19, as shown in the figure above. If a female of this species has one chromosome 12 with a blue gene and another chromosome 12 with an orange gene, and has both number 19 chromosomes with short genes, she will produce which of the following egg types?

one-half blue short and one-half orange short gene eggs

For what purpose(s) might a karyotype be prepared?

to determine whether a fetus is male or female, for prenatal screening, to determine if a fetus has the correct number of chromosomes, to detect the possible presence of chromosomal abnormalities such as deletions, inversions, or translocations