AP Biology : Cellular Biology

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #273 : Cell Functions

When does crossing over happen in meiosis? 

Possible Answers:

Metaphase I

Prophase II

Anaphase I

Metaphase II

Prophase I

Correct answer:

Prophase I

Explanation:

The exchange of genetic material happens during the prophase I of meiosis. We know that since meiosis I involves the pairing, crossing over, and separation of homologous chromosomes, our answer must be in meiosis I. During metaphase I, the tetrads line up along the metaphase plate, and during anaphase they begin to be pulled to opposite sides of the cell by spindle fibers.

Example Question #52 : Understanding Meiosis

Which of the following describes when crossing over occurs during meiosis?

Possible Answers:

Prophase I

Metaphase I

Prophase II

Metaphase II

Anaphase I

Correct answer:

Prophase I

Explanation:

In prophase I, homologous chromosomes pair up and facilitate the exchange of genetic information through the process of crossing over.

Example Question #274 : Cell Functions

In regards to DNA, how does a cell prepare for cell division?

 DNA is __________ to create two __________ per __________, which are connected at the __________.

Possible Answers:

replicated . . . sister chromatids . . . chromosome . . . centromere 

replicated . . . sister chromosomes . . . chromatid . . . centromere

replicated . . . homologous chromatids . . . chromosome . . . centriole

replicated . . . homologous chromosomes . . . chromatid . . . centromere 

replicated . . . homologous chromosome . . . chromatid . . . centriole

Correct answer:

replicated . . . sister chromatids . . . chromosome . . . centromere 

Explanation:

In preparation for cell division, DNA is copied (replicated) to create chromosomes with two identical sides (sister chromatids), which are connected at the centromere. DNA must be replicated before prophase, in S phase of interphase. Do not be confused with the terms centrioles, centrosomes, and centromere. Centrioles are located at centrosomes, which are found at opposite poles of the cell during meiosis stages of prophase, metaphase, anaphase, and telophase. The question is asking about interphase, which is prior to the meiosis/mitosis stages. 

Example Question #381 : Cellular Biology

Which of the following is not a function of mitosis? 

Possible Answers:

Mitosis allows for organisms to grow

Mitosis allows for repair of damaged tissues 

Mitosis contributes to genetic diversity in sexual organisms 

Mitosis is the process by which asexual organisms reproduce

All of these are functions of mitosis

Correct answer:

Mitosis contributes to genetic diversity in sexual organisms 

Explanation:

For homogenous or identical cells of a particular tissue, mitosis allows for the restoration of lost or damaged tissue by resulting in identical daughter cells which can replace lost cells. The same is true for an asexual population. The process of mitosis has several checkpoints to ensure fidelity with each round of copied cells. Meiosis, on the other hand, tries to ensure evolutionary fitness of a sexually reproducing population by introducing a variety of genetic alleles per gamete which will result in fertilization to create a unique individual. Therefore, mitosis allows for growth, restoration of damaged tissue, asexual reproduction (for example, bacteria!) and does not result in genetic variety.

Example Question #451 : Ap Biology

Which of the following contribute to genetic diversity?

Possible Answers:

Meiosis, independent assortment of sister chromatids, and chromosomal crossover 

Meiosis, independent assortment of homologous chromosomes, and chromosomal crossover

Mitosis, independent assortment of homologous chromosomes, and chromosomal crossover

Meiosis, nondisjunction, and chromosomal crossover

Mitosis, nondisjunction, and chromosomal crossover

Correct answer:

Meiosis, independent assortment of homologous chromosomes, and chromosomal crossover

Explanation:

Meiosis, which includes independent assortment of homologous chromosomes and chromosomal crossover, contributes to genetic diversity. Independent assortment of chromosomes is the random distribution of one chromosome per homologous chromosomal pair to each daughter cell during anaphase I. Chromosomal crossover, which begins in prophase I, results in genetic recombination between each tetrad (homologous chromosomes). Nondisjunction is not a correct option as this typically results in large scale genetic abnormalities and infertility which subsequently does not contribute to a population's long-term genetic diversity. 

Example Question #452 : Ap Biology

Select the answer choice with the correct terms. 

In human female gametogenesis __________ occurs which results in only one functional gamete called a(n) __________ due to __________.

Possible Answers:

meiosis . . . sperm . . . unequal division of cytoplasm

meiosis . . . ovum . . . nondisjunction 

meiosis . . . ovum . . . unequal division of cytoplasm

mitosis . . . ovum . . . unequal division of cytoplasm

meiosis . . . sperm . . . nondisjunction

Correct answer:

meiosis . . . ovum . . . unequal division of cytoplasm

Explanation:

Human female gametogenesis occurs through meiosis and results in three non-functional daughter cells known as polar bodies and one functional and much larger daughter cell called an ovum. Unequal division of cytoplasm during meiosis I and meiosis II towards only one of the daughter cells results in the ovum. Non-disjunction is the unequal assortment of chromosomes, not cytoplasm. Human female gametogenesis results in ovum while human male gametogenesis results in sperm. Mitosis does not result in gamete daughter cells but identical daughter cells as mitosis occurs in somatic (body or non-germ cells) cells. 

Example Question #64 : Understanding Meiosis

Which of the following cells will undergo meiosis? 

Possible Answers:

All of these

Heart cells

Amoebae

Germ cells

Unicellular organisms

Correct answer:

Germ cells

Explanation:

Germ cells give rise to gametes through meiosis. All of the other organisms listed are asexually reproducing organisms and therefore only undergo mitosis. 

Example Question #161 : Cellular Division

In which two phases can nondisjunction occur?

Possible Answers:

Metaphase I and metaphase II 

Anaphase I and anaphase II

Metaphase I and anaphase II

Anaphase I and metaphase II

Telophase I and telophase II

Correct answer:

Anaphase I and anaphase II

Explanation:

Nondisjunction of homologous chromosomes may occur in anaphase I and nondisjunction of sister chromatids may occur in anaphase II. 

Example Question #162 : Cellular Division

Which of the following is the basis for independent assortment of homologous chromosomes?

Possible Answers:

Spindles align chromosomes randomly in anaphase  I 

Recombination occurs in telophase I 

Chromosomes are paired into tetrads in prophase I 

Homologous chromosomes line up randomly at the metaphase plate in metaphase I 

Homologous chromosomes undergo crossover in prophase I 

Correct answer:

Homologous chromosomes line up randomly at the metaphase plate in metaphase I 

Explanation:

Independent assortment depends upon random alignment of homologous chromosomes in metaphase I which will result in randomly assorted chromosomes into two daughter cells at the end of meiosis I. Crossover, or recombination, occurs in prophase I which contributes to genetic diversity, but does not affect random alignment of homologous chromosomes. Spindles align chromosomes randomly in metaphase I, not anaphase I during which they are already "aligned" and are moving towards opposite poles of the cell.

Example Question #163 : Cellular Division

In the process of meiosis, what is the correct description of the gametes?

Possible Answers:

The gametes are diploid, with half the number of chromosomes compared to the parent cell

The gametes are diploid, with twice the number of chromosomes compared to the parent cell

The gametes are haploid, with half the number of chromosomes compared to the parent cell

The gametes are polyploid

Correct answer:

The gametes are haploid, with half the number of chromosomes compared to the parent cell

Explanation:

In meiosis, the gametes are haploid having half the number of chromosomes of a diploid cell.  The gametes are the egg or sperm cells that combine in sexual reproduction.

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