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Biology & Life Science
Q:
Explain why a life cycle that includes meiosis must also include fertilization. What is the advantage of such a life cycle?
Q:
What features of spermatogonia allow males to produce sperm throughout most of their lives? What would happen if the spermatogonia, instead of producing more spermatogonia, divided and produced four gametes?
Q:
Describe the process of meiosis and ova formation in a human female; start with prenatal life, and end with fertilization.
Q:
Describe how sperm and egg cells are different from somatic cells in number of chromosomes (in humans), the cell division processes they undergo and the process that generates them, and the process they undergo to generate a zygote.
Q:
In meiosis, X and Y chromosomes will pair as homologous chromosomes, but they will recombine only in a few limited regions, at the ends. Explain why recombination is limited in this situation.
Q:
Different species can sometimes interbreed to produce hybrid offspring. For example, the breeding of a horse with a donkey produces a mule. However, these hybrids are usually sterile. A horse will produce gametes with 32 chromosomes, and a donkey will produce gametes with 31 chromosomes, resulting in a mule with 63 chromosomes. Using your understanding of meiosis, propose a reason why mules are sterile.
Q:
Errors in meiosis can be one mechanism of evolution. A change in the number of chromosomes can lead to the production of new species. Some plant species may have originated from errors during cell division, which led to them having more than two sets of chromosomes, a condition called polyploidy. Hypothesize what kind of error during meiosis might occur to cause a normally diploid plant to generate tetraploid offspring, in which the offspring have four sets of chromosomes.
Q:
Suppose a researcher claims to be able to make a hybrid animal that is a cross between a human and a rhesus monkey. The normal diploid number for humans is 46, and the normal diploid number for rhesus monkeys is 48. Based on normal meiosis, how many chromosomes would the human gamete have, and how many chromosomes would the rhesus monkey have? Given these numbers, how many chromosomes would you expect the hybrid embryo to contain?
Q:
________ have both male and female reproductive parts.
Q:
Once produced, a zygote will divide by ________ to develop into a whole organism.
Q:
The haploid number of an organism is 20. A somatic cell from this organism has ________ chromosomes, and its gametes have ________ chromosomes.
Q:
The primary purpose of meiosis is to ________ the number of chromosomes; meiosis also generates ________ in the resulting cells.
Q:
________ is the process in which a single diploid cell divides to produce haploid reproductive cells.
Q:
Match the following.A) anaphase IB) metaphase IIC) anaphase IID) prophase IE) metaphase IRandom alignment of maternal and paternal homologous chromosomes results in independent assortment
Q:
Match the following.A) anaphase IB) metaphase IIC) anaphase IID) prophase IE) metaphase IRecombination occurs
Q:
Match the following.A) anaphase IB) metaphase IIC) anaphase IID) prophase IE) metaphase IHomologous chromosomes separate
Q:
Match the following.A) anaphase IB) metaphase IIC) anaphase IID) prophase IE) metaphase IPairs of sister chromatids line up at the equator, with each one facing opposite poles
Q:
Match the following.A) anaphase IB) metaphase IIC) anaphase IID) prophase IE) metaphase ISister chromatids separate
Q:
The X and Y chromosomes are not homologous, but in the meiosis of sperm formation, they pair and separate in anaphase I as though they were homologous.
Q:
If an egg is fertilized by a sperm carrying an X chromosome, the resulting child might be either a boy or a girl, depending on the sex chromosome carried by the egg.
Q:
In humans, the sperm contributes the chromosome that determines whether the child will be a boy or a girl.
Q:
In recombination (crossing over), DNA is exchanged between homologous, non-sister chromatids.
Q:
At the end of meiosis I, each of the sister chromatids is considered a full-fledged chromosome.
Q:
The number of chromosomes present in a cell in metaphase I and metaphase II is the same.
Q:
The number of chromosomes present in a human cell at anaphase of mitosis and anaphase of meiosis II is the same.
Q:
When a cutting from a plant sprouts roots and yields a new, independent plant, what process has occurred?
A) sexual reproduction
B) self-fertilization
C) recombination
D) asexual reproduction
E) cytokinesis
Q:
Bacteria (prokaryotes) divide by ________ reproduction, and eukaryotes reproduce by ________ reproduction.
A) sexual; asexual
B) either asexual or sexual; either asexual or sexual
C) sexual; either asexual or sexual
D) asexual; both asexual and sexual
E) asexual; sexual
Q:
A plant branch that regenerates roots and develops into another plant is:
A) genetically unique.
B) the product of a special type of sexual reproduction.
C) the product of self-fertilization.
D) the product of a recombination event.
E) genetically identical to the plant from which the branch was taken.
Q:
At what two stages in the human life cycle are diploid cells found?
A) in adult humans and as the zygote
B) as the zygote and in the sperm and eggs
C) in gametes and in sperm and eggs
D) in adult humans and in sperm and eggs
E) in gametes and as the zygote
Q:
From an evolutionary perspective, why is sexual reproduction advantageous over asexual reproduction?
A) Sexual reproduction is faster and easier than asexual reproduction.
B) Asexual reproduction minimizes differences, so natural selection can act more easily.
C) Sexual reproduction produces greater genetic diversity than asexual reproduction.
D) Sexual reproduction produces less genetic diversity than asexual reproduction.
Q:
In humans, which cells undergo meiosis?
A) polar bodies
B) oogonia and spermatogonia
C) zygotes
D) primary oocytes and spermatocytes
E) sperm and eggs
Q:
From the list below, which choice represents a correct difference between sperm production and egg production?
A) Sperm are produced by mitosis; eggs are produced by meiosis.
B) Sperm are produced by meiosis; eggs are produced by mitosis.
C) Four mature sperm are produced from one cell; one large egg is produced from one cell.
D) Eight mature sperm are produced from one cell; two eggs are produced from one cell.
E) Sperm are produced by somatic (body) cells; eggs are produced by gametes.
Q:
Spermatogonia are called stem cells because they develop into two different types of cells. What are they?
A) primary spermatocytes and sperm
B) more spermatogonia and primary spermatocytes
C) polar bodies and oocytes
D) more spermatogonia and oocytes
E) polar bodies and sperm
Q:
What is the flagellum in sperm for?
A) to provide a diploid set of chromosomes
B) for energy production
C) to provide a haploid set of chromosomes
D) to serve as a structure for the physical propulsion of the sperm
E) to serve as a reserve of energy and nutrients for the zygote
Q:
When does an oocyte complete meiosis II?
A) in the seventh month of fetal life
B) immediately after release from the ovary
C) immediately after birth
D) after fertilization
E) as soon as puberty begins
Q:
In a human zygote, where did most of the cytoplasm come from?
A) sperm
B) oocyte
C) spermatogonia
D) polar bodies
Q:
What is one of the cellular differences between human eggs and sperm?
A) Sperm are arrested in meiosis II; eggs have completed meiosis.
B) Eggs have 200,000 times the volume of sperm.
C) Sperm contain a haploid set of chromosomes; eggs are diploid.
D) Sperm are arrested in meiosis I; eggs have completed meiosis.
E) Sperm have 200,000 times the volume of eggs.
Q:
Refer to the figure below, and then answer the question that follows.A cell that no longer needs to divide will remain in G0phase. But if an injury occurs to an organ, signals will tell the cell to return to the cell cycle to replace lost or damaged cells. To which point in the cycle will the cell return, and which phase would it enter next?
Q:
Refer to the figure below, and then answer the question that follows. What is the advantage of chromatin coiling and condensing into tight structures before mitosis?
Q:
List and briefly describe three differences between prokaryotic and eukaryotic cell division.
Q:
You are a physician treating a patient with cancer. Traditional chemotherapy has not been working on this patient, so you prescribe a new class of drugs called taxanes, which inhibit microtubule function. Your patient asks you how they work. How would you explain to your patient how these drugs work?
Q:
During which phase of mitosis are the chromosomes aligned along the equator of the cell? Predict what would happen if a cell completed mitosis without first lining up all the chromosomes in the middle of the cell.
Q:
Each phase of the cell cycle takes a different amount of time for a cell to complete. The longer the length of the phase, the more likely you will find a cell in that phase. You are looking at some animal cells under the microscope, and you see cells at different phases of the cell cycle. You count how many are in each phase and find out that 90 percent are in interphase, 6 percent are in prophase, 1.5 percent are in metaphase, 0.5 percent are in anaphase, and 2 percent are in telophase. If the length of the cell cycle is 24 hours, how long does it take for the cells to go through each of these phases of the cell cycle?
Q:
At several points in the cell cycle there are checkpoints that control the cell's passage from one phase to the next. If a cell receives a signal at each checkpoint, it continues to the next phase; if it does not receive the signal, the cell does not continue. For example, a growth factor may stimulate a cell to move from G1into S phase. If no growth factor is present, the cell cycle stops in G1and the cell does not divide. Predict what would happen to a cell and to a multicellular organism if there was a defect at the checkpoint and the cell continued through the cell cycle even in the absence of a signal.
Q:
What is the relationship between genes and proteins, including the function of each?
Q:
Human skin cells and human white blood cells of the immune system both perform protective functions. Skin cells function primarily in external physical protection, whereas white blood cells function primarily in internal protection. Nonetheless, both types of cells contain a complete copy of the human genome. Explain how cells can have the same genetic information and yet perform different functions. What prevents skin cells from making all the same proteins of a white blood cell?
Q:
In cell division, the separation of the cell's cytoplasm to produce two daughter cells is ________.
Q:
Answer: mitosis
Q:
The ________ is a microtubule structure that binds to sister chromatids to separate them in anaphase.
Q:
The sequence of events from the birth of a cell to when it divides describes the ________.
Q:
The ________ of an organism is its complete collection of genetic information.
Q:
Match the following.A) metaphaseB) telophaseC) prophaseD) cytokinesisE) anaphaseChromosomes unwind and new nuclei form
Q:
Match the following.A) metaphaseB) telophaseC) prophaseD) cytokinesisE) anaphaseA contractile ring is narrowing along the cell's equator
Q:
Match the following.A) metaphaseB) telophaseC) prophaseD) cytokinesisE) anaphaseThe nuclear envelope has disappeared completely and sister chromatids are facing opposite poles
Q:
Match the following.A) metaphaseB) telophaseC) prophaseD) cytokinesisE) anaphaseMicrotubules shorten and the genetic material divides
Q:
Match the following.A) metaphaseB) telophaseC) prophaseD) cytokinesisE) anaphaseChromosomes condense and the mitotic spindle begins to form
Q:
During the cytokinesis phase of cell division, plant cells develop a cell plate instead of a cleavage furrow.
Q:
Bacterial binary fission is essentially the same process as mitosis in animals and plants.
Q:
The chief accomplishment of telophase is the organization of chromosomes into new nuclei.
Q:
When a dividing human cell reaches telophase, 23 nuclear membranes must form, one for each pair of chromosomes.
Q:
During the cell cycle of a eukaryotic cell, each chromosome is replicated to become a chromosome with two chromatids, and then the chromatids are pulled apart to form two separate chromosomes.
Q:
Compact chromosomes first become visible during metaphase.
Q:
Anaphase is characterized by the separation of sister chromatids.
Q:
The human genome is estimated to include 20,000 to 25,000 genes.
Q:
A cell plate is forming across the middle of a cell and new nuclei are forming at the poles. What kind of cell is this?
A) an animal cell going through cytokinesis
B) an animal cell during telophase
C) a bacterial cell
D) a plant cell during metaphase
E) a plant cell going through cytokinesis
Q:
Which of the following organisms would reproduce by binary fission?
A) plants
B) animals
C) fungi
D) bacteria
Q:
Which statement about binary fission is true?
A) It occurs during S phase of the cell cycle.
B) It is the cell division process of both prokaryotic and eukaryotic cells.
C) It is the cell division process of prokaryotic cells.
D) It is part of interphase.
Q:
What is one of the similarities between prokaryotic and eukaryotic cell division?A) DNA is unwound and duplicated by the same process.B) Microtubules separate the chromosomes.C) One cell divides into four cells.D) At the end of cell division, nuclear membranes form around the chromosomes.
Q:
What is one of the differences between cell division in plant cells and cell division in animal cells?
A) Plant cells separate chromosomes by attachment to the plasma membrane.
B) There is no DNA replication before cell division in plant cells.
C) Plant cells do not use a mitotic spindle to separate chromosomes.
D) Plant cells separate by the formation of a new plasma membrane and cell wall in the middle of the cell.
Q:
Why is prokaryotic cell division fundamentally different from eukaryotic cell division?
A) Prokaryotic cells divide for several months and then live for decades without dividing.
B) Prokaryotic cells do not have a plasma membrane.
C) Prokaryotes have many more chromosomes to divide.
D) Prokaryotic cells have a single chromosome and no nuclear membrane.
Q:
How do daughter cells at the end of mitosis and cytokinesis compare with the parent cell before DNA replication occurs?
A) The daughter cells may have the same number of chromosomes but double the amount of DNA.
B) The daughter cells have the same number of chromosomes and the same amount of DNA.
C) The daughter cells have half the number of chromosomes and half the amount of DNA.
D) The daughter cells have half the amount of cytoplasm and half the number of chromosomes.
Q:
Chromosomes uncoil and new nuclei form during:
A) prophase.
B) metaphase.
C) anaphase.
D) telophase.
Q:
While looking under a microscope, you see two neighboring daughter cells. One of the cells contains three chromosomes, and the other contains five. The parent cell normally contains four chromosomes. What could be the reason for the different number of chromosomes in the cells?
A) The division of sister chromatids of one chromosome did not occur properly during mitosis.
B) The nuclear envelope did not dissolve, so mitosis could not occur at all.
C) Replication of DNA did not occur properly.
D) The division of homologous chromosomes during meiosis II did not occur properly.
Q:
What would happen if the cell cycle proceeded normally except cytokinesis did not occur?
A) The absence of cytokinesis would inhibit mitosis.
B) The G1 and G2 phases would become shorter.
C) Cells without nuclei would be formed.
D) A large cell with multiple nuclei would result.
Q:
If a cell with 16 chromosomes undergoes mitosis, how many chromosomes will each daughter cell have?
A) 8
B) 4
C) 32
D) 16
Q:
A cell is observed under the microscope. What feature will indicate that it is in anaphase?
A) DNA is elongated, not condensed, and difficult to visualize.
B) Two separate nuclear membranes are visible.
C) Centrosomes are just beginning to separate and form the spindle.
D) Sister chromatids are separating.
Q:
A cell is observed under the microscope. What feature will indicate that it has just reached the end of interphase?
A) a visible contractile ring
B) two separate cells
C) elongated, noncondensed chromosomes that are difficult to visualize
D) chromosomes that are becoming well defined and visible
Q:
Sister chromatids are separating from each other during:
A) prophase.
B) metaphase.
C) anaphase.
D) telophase.
Q:
Which statement is true of mitosis and cytokinesis in normal tissues?
A) Cytokinesis partially overlaps with mitosis.
B) Cytokinesis occurs simultaneously with mitosis.
C) Mitosis precedes cytokinesis.
D) Cytokinesis precedes mitosis.
Q:
The chromosomes become visible and the nucleus starts to break up during:
A) prophase.
B) metaphase.
C) anaphase.
D) telophase.