Bio exam 3

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Lipid-soluble signaling molecules, such as testosterone, cross the membranes of all cells but affect only target cells because

intracellular receptors are present only in target cells

The centromere is a region in which

chromatids remain attached to one another until anaphase

Movement of the chromosomes during anaphase would be most affected by a drug that prevents

prevents shortening of microtubules.

If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis?

10

If there are 20 chromatids in a cell, how many centromeres are there?

10

A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. How many picograms would be found at the end of S and the end of G2?

16; 16

Starting with a fertilized egg, a series of five cell divisions would produce an early embryo with how many cells?

32

When a cell is an anaphase of mitosis which of the following will he see?

A clear area in the center of the cell

Which of the following is an example of alteration of generations?

A diploid plant (sporophyte) produces, by meiosis, a spore that gives rise to a multicellular, haploid pollen grain (gametophyte).

In the human species, are somatic cells have 46 chromosomes. Which of the following can also be true?

A plant species has 46 chromosomes per cell

Which of the following can utilize both meiosis and mitosis in the correct circumstances?

A plantlike protist

Which of the following is required for motor proteins function in the movement of chromosomes toward the poles of the mitotic spindle?

ATP as an energy source

Centromere's of sister chromatids disjoint and chromatids separate

Anaphase II

Density dependent inhibition is explained by which of the following?

As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing.

If an organism is deployed and a certain gene found in the organism has 18 known alleles, then any given organism of that species can have which of the following?

At most, two alleles for that Gene

Which of these statements is false?

At sexual maturity, ovaries and testes produce diploid gametes by meiosis.

For a newly evolving protest, what would be the advantage of using eukaryote like cell division rather than binary fission?

Cell division would allow for the orderly and efficient segregation of multiple linear chromosomes

Where do the microtubules of the spindle originate during meiosis in both plant and animal cells?

Centrosome

Cells from an advanced malignant tumor most often have very abnormal chromosomes, and often an abnormal total number of chromosomes. Why might this occur?

Chromosomally abnormal cells can still go through cell cycle checkpoints.

The drug cytochalasin B blocks the function of Acton. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B?

Cleavage furrow formation and cytokinesis

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

Clone the plant asexually to produce an identical one.

For anaphase to begin, which of the following must occur?

Cohesin must be cleaved enzymatically.

Once they had determine which cells were dividing, between wanted to use a non-radioactive method to track with various physiological factors affect the action of the pathogen. Which of the following would be effective, simple, and safe?

Counting the frequency of cells in mitosis

Which of the following is a protein synthesized at specific times during the cell cycle that forms a catalytically active complex?

Cyclin

To view and analyze human chromosomes in a dividing cell, which of the following is required?

DNA stain and a light microscope

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

Each cell has eight homologous pairs.

A particular cell has half as much DNA as some cells in a mitotically active tissue. The cell in question is most likely in

G1

After which checkpoint is the cell first committed to continue the cell cycle through M?

G1

Measurement of the amount of DNA per nucleus were taken on a large number of cells from growing fungus. The measure do you know levels range from 3 to 6 pictograms per nucleus. In which state of the cell cycle to the nucleus contains six pictograms of DNA?

G2

The somatic cells of a privet shrub each contain 46 chromosomes. To be as different as they are from human cells, which have the same number of chromosomes, which of the following must be true?

Genes of privet chromosomes are significantly different than those in humans

After Telophase 1 of meiosis, the chromosomal make up of each daughter cell is

Haploid, and the chromosomes Are each composed of two chromatids.

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

Homologous chromosomes are separated

Which of the following is a true statement about sexual versus asexual production?

In sexual production, individuals transmit 50% of their genes to each of their offspring.

If a cell has completed the first meiotic division and is just beginning meiosis II, which of the following is an appropriate description of its contents?

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

For a chemotherapeutic drug to be useful for treating cancer cells, which of the following is most desirable?

It interferes with rapidly dividing cells.

A given organism has 46 chromosomes in its karyotype. We can therefore conclude which of the following?

Its gametes must have 23 chromosomes.

You have a series of cells, all of which were derived from tumors, and you first need to find out which ones are malignant. What could you do?

Karyotype samples to look for unusual size and number of chromosomes.

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 do the two chromosomes and the pear have in common?

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

Why is apoptosis potentially threatening to the healthy neighbors of a dying cell?

Lysosomal enzymes exiting the dying cell would damage surrounding cells

Which of the following is a function of those spindle microtubules that do not attach to kinectochores?

Maintaining the region of overlap of microtubules in the cells center

Homologous chromosomes move to opposite poles of a dividing cell during

Meiosis I

Eukaryotic sexual lifecycles show tremendous variation. The following elements, which do all sexual lifecycles have in common?

Meiosis, fertilization, and gametes

Tetrads of chromosomes are lined at the equator of the spindle; alignment determines independent assortment.

Metaphase I

Synaptonemal complexes form or are still present.

Prophase I

When we see chiasmata under a microscope, that lets us know which of the following has occurred?

Prophase I

Which of The following does not occur during mitosis?

Replication of the DNA

At the M phase checkpoint, the complex allows for what to occur?

Separase enzyme cleaves cohesins and allows chromatids to separate.

Which of the following steps takes place in both mitosis and meiosis?

Separation of sister chromatids

To visualize and identify meiotic cells at metaphase with a telescope, what would you look for?

Tetrads all aligned at the cells center

A mutation results in a cell that no longer produces a normal protein kinase for the M phase checkpoint. Which of the following would likely be the immediate result of this mutation?

The cell would undergo normal mitosis, but fail to enter the next G1 phase.

A research team began a study of a cultured cell line. Their preliminary observations showed them that the cell line did not exhibit either density-dependent inhibition or anchorage dependence. What could they conclude right away?

The cells show characteristics of tumors.

Which of the following best describes how chromosomes move toward the poles of the spindle during mitosis?

The chromosomes are "reeled in" by the contraction of spindle microtubules, and motor proteins of the kinetochores move the chromosomes along the spindle microtubules.

A plant-derived protein known as colchicine can be used to poison cells by blocking the formation of the spindle. Which of the following would result if colchicine is added to a sample of cells in G2?

The chromosomes would coil and shorten but have no spindle to which to attach.

The research team establish similar lymphocyte cultures from a number of human donors. They found that the increase in lymphocyte incorporation after pathogen introduction was slightly lower and some of the female teenagers and significantly lower in each of the elderly persons. They repeated the study with a larger number of samples we got the same results. What might be among the research teams conclusions?

The elderly persons samples demonstrated their lowered immune responses

A cell divides to produce two daughter cells that are genetically different.

The statement is true for meiosis I only.

Independent assortment of chromosomes occurs

The statement is true for meiosis I only.

Chromatids are separated from each other

The statement is true for mitosis and meiosis II.

All cell cycle checkpoints are similar in which way?

They activate or inactivate other proteins.

Why do neurons and some other specialized cells divide in frequently?

They have been shunted into G0.

How do you cells at the completion of my house is comparable sales that have replicated the DNA and are just about to begin meiosis?

They have half the number of chromosomes and 1/4 the amount of DNA.

Weather during mitosis or meiosis, sister chromatids are held together by proteins referred to as cohesions. Search molecules must have which of the following properties?

They must be removed before anaphase can occur

Several organisms, primarily protists, have what are called intermediate mitotic organization. These protists are intermediate in what sense?

They show some but not all of the evolutionary steps toward complete mitosis

When the cell has just completed Tele phase, which of the following does he see?

Two small cells with chromatin

Which of the following is true concerning cancer cells?

When they stop dividing, they do so at random points in the cell cycle; they are not subject to cell cycle controls; and they do not exhibit density-dependent inhibition when growing in culture.

What is a cleavage furrow?

a groove in the plasma membrane between daughter nuclei

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

a plant cell in the process of cytokinesis.

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

about 8 million

Which of the following proteins are involved in binary fission as well as eukaryotic mitotic division?

actin and tubulin

Which of the following might result in a human zygote with 45 chromosomes?

an error in either egg or sperm meiotic anaphase

Which of the following best describes a frequency of crossing over in mammals?

at least 1-2 per chromosome pair

How does the sexual life cycle increase the genetic variation in a species?

by allowing crossing over

In the cells of some organisms, mitosis occurs without cytokinesis. This will result in

cells with more than one nucleus

Where do the microtubules of the spindle originate during mitosis in both plant and animal cells?

centrosome

Experiments with cohesions have found that

cohesions are protected from cleavage at the centromere during meiosis I.

One Difference between cancer cells in normal cells is that cancer cells

continue to divide even when they are tightly packed together.

One difference between cancer cells in normal cells is that cancer cells

continue to divide even when they are tightly packed together.

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to

disruption of mitotic spindle formation.

The karyotype of one species of primate has 48 chromosomes. In a particular female, cell division goes awry and she produces one of her eggs with an extra chromosome (25). The most probable source of this error would be a mistake in which of the following?

either anaphase I or II

The human genome is minimally contained in which of the following?

every human cell

Referring to a plant sexual life cycle, which of the following terms describes the process that leads directly to the formation of gametes?

gametophyte mitosis

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

haploid, and the chromosomes are each composed of two chromatids

The human X and Y chromosomes

include genes that determine an individual's sex

Nucleotides can be radiolabeled before they are incorporated into newly forming DNA and can therefore be assayed to track their incorporation. In a set of experiments, a student-faculty research team used labeled T nucleotides and introduced these into the culture of dividing human cells at specific times. The research team used the setup to study the incorporation of labeled nucleotides into a culture of lymphocytes and found that the lymphocytes incorporated the labeled nucleotide at a significantly higher level after a pathogen was introduced into the culture. They concluded that

infection causes lymphocytes to divide more rapidly

Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor?

lack of appropriate cell death

When does the synaptonemal complex disappear?

late prophase of meiosis I

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 do the two chromosomes of the pair have in common?

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

At which stage of mitosis are chromosomes usually photographed in the preparation of a karyotype?

metaphase

If cells in the process of dividing are subjected to colchicine, a drug that interferes with the formation of the spindle apparatus, at which stage will mitosis be arrested?

metaphase

You have the technology necessary to measure each of the following in a sample of animal cells: chlorophylls, organelle density, picograms of DNA, cell wall components, and enzymatic activity. Which would you expect to increase significantly from M to G1?

organelle density and enzymatic activity

At which phase are centrioles beginning to move apart in animal cells?

prophase

Which of the following does not occur during mitosis?

replication of DNA

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

synapsis of chromosomes

During which phase of mitosis do the chromatids become chromosomes?

telophase

Which of the following defines a genome?

the complete set of an organism's genes

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin. Surprisingly, this stops mitosis. Specifically, Taxol must affect

the formation of the mitotic spindle

A karyotype results from which of the following?

the ordering of human chromosome images

Independent assortment of chromosomes is a result of

the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I.

Why do chromosomes coil during mitosis?

to allow the chromosomes to move without becoming entangled and breaking

Suppose a biologist can separate one of a dozen pieces of chromatin from a eukaryotic (animal) nucleus. It might consist of which of the following?

two long strands of DNA plus proteins

A tetrad includes which of the following sets of DNA strands?

two sets of sister chromatids that have synapsed


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