Bio Exam 2

What purpose does crossing over and independent assortment play in cell division?

a. To help add genetic diversity to daughter cells FEEDBACK: Along with random fertilization, these processes help to promote genetic diversity among daughter cells. Diversity is important since it is the raw material that drives the process of evolution.

Glycolysis takes place in the ___ and produces ___ which in the presence of 02 then enters the ___

a. cytoplasm; pyruvate; mitochondrion to complete cellular respiration FEEDBACK: Glycolysis is the only portion of cellular respiration that occurs outside the mitochondria. If oxygen is present, pyruvate can enter the mitochondrion to complete cellular respiration.

The three stages of cellular respiration (in order) are

a. glycolysis, the Krebs cycle, and oxidative phosphorylation

An actively dividing cell has six chromosomes. How many sister chromatids are present within this cell at the end of G2 phase?

a. 12

A chromosome consists of

a. DNA wound tightly around proteins FEEDBACK: A chromosome is a DNA-protein complex. DNA is packaged around histone proteins into a compact structure.

Replication of a cell's genetic material occurs during

a. S phase FEEDBACK: Prior to cell division, cells duplicate their genetic material. This occurs during the "synthesis" or S phase of interphase.

Homologous chromosomes

a. consist of a maternal and paternal copy of each chromosome

(a picture of 2 x's crossed) The structure circled in the figure is a

a. duplicated chromosome FEEDBACK: In preparation for cell division, chromosomes are copied during S phase to produce duplicated chromosomes, in which two identical sister chromatids are held together at the centromere and form an X shape. A single, unduplicated chromatid resembles a single line.

Mutations will affect the

a. genotype, which may affect the phenotype

Gametes are produced by meiosis rather than mitosis because

a. meiosis reduces the chromosome number so that zygotes produced will have one full genome.

Which of the following is a reason why a cell might undergo mitosis

b. To repair damaged tissues FEEDBACK: Mitosis is used for asexual reproduction, organism growth, and repair of tissues. Production of egg and sperm cells and increased genetic diversity are accomplished through meiosis.

Which of the following is closely associated with mitochondria?

b. Krebs Cycle FEEDBACK: Chloroplasts (not mitochondria) contain thylakoids. The Calvin cycle occurs in the chloroplast while the Krebs cycle occurs in the mitochondria. Glycolysis occurs in the cytoplasm.

The figure shown indicates a homologous pair of chromosomes. Which of the following indicates the relationship between Gene A and the circled gene?

b. The circled gene must encode information for the same trait as Gene A. FEEDBACK: Remember that homologous pairs are inherited when each parent passes one chromosome on to offspring. Genes in the same location on homologous chromosomes carry information for the same traits. The alleles on each chromosome in the pair may be the same or different.

A female who is a carrier for an autosomal recessive disorder has the genotype

b. Tt FEEDBACK: Carriers of an autosomal recessive disorder are heterozygous for alleles that are not on the sex chromosomes.

Why are autosomal dominant disorders rarer than autosomal recessive disorders?

b. an allele for an autosomal dominant disorder cannot "hide" in someone who is heterozygous, so it is less likely to be passed down. dominant disorder cannot "hide" in someone who is heterozygous, so it is less likely to be passed down.

During which of the following phases of mitosis do replicated chromosomes line up at an invisible plane along the center of the cell?

b. metaphase FEEDBACK: During mitosis, replicated chromosomes are pushed back and forth until they wind up in the center of the cell. The mitotic spindle is the structure that relocates chromosomes in this fashion. At metaphase the replicated chromosomes line up at the metaphase plate, an invisible plane along the center of the cell

The molecule ________ is produced to carry energy and is broken down during cellular processes to use that energy.

c. ATP FEEDBACK: ATP fuels metabolic reactions. Energy is released when it is broken down to ADP and a free phosphate.

How do the chromosomes in a male human differ from those in a female human

c. Males have a Y chromosome, which females lack. FEEDBACK: Males have one X chromosome and one Y chromosome. Females have two X chromosomes.

A man and his wife are both carriers for a recessive disease allele. If the couple has a child, which of the following statements is true?

c. The child has a 25 percent chance of being affected by the disease. FEEDBACK: Carriers have one copy of the recessive disease allele and one copy of the dominant allele. The chance of a child receiving a recessive allele from one parent is 1/2 or 50 percent. The chance of a child inheriting recessive disease alleles from both parents is 1/2 multiplied by 1/2 or 1/4 (25 percent).

The chromosomes in a homologous pair

c. carry the same genes

Most human genetic characters are

c. controlled by more than one gene

Mendel's breeding experiments with pea plants indicate that alleles of a gene separate during

c. meiosis FEEDBACK: The event responsible for the law of segregation occurs in meiosis, when homologous chromosomes separate into different daughter cells. The law of independent assortment, which states that two alleles segregate independently of any two alleles of another gene, is also based on events that occur during meiosis.

During Cellular Respiration, ____is the step that produces the greatest number of ATP molecules

c. oxidative Phosphorylation Feedback: over 80% of the ATP produced during cellular respiration is the result of oxidative phosphorylation

The ultimate source of energy for most living systems is

c. sunlight FEEDBACK: Although glucose is used by cells to produce ATP, the glucose must first be made through photosynthesis. Sunlight provides the energy needed to make glucose through the process of photosynthesis. Organisms that perform photosynthesis, like plants, some bacteria, and some protozoans, can use this glucose directly, while organisms that eat photosynthesizers or other consumers get this glucose indirectly

What is indicated by the arrow in the figure shown? (showing a punnett square)

c. the alleles in an offspring FEEDBACK: A Punnett square is used to indicate the separation of parental alleles into gametes and to show the possible combinations of these alleles in offspring. Each allele is represented by a letter.

A short sequence of bases on one strand of DNA is AGTCTACCGATAGT. If this sequence serves as a template for the formation of a new strand of DNA, what will be the corresponding base sequence in the new strand?

c.TCAGATGGCTATCA FEEDBACK: According to the base-pairing rules, A pairs to T and G pairs to C in DNA replication.

During exercise, the increase in respiration rate and heart rate are driven by the need to replenish the oxygen used to support

d. oxidative phosphorylation in muscle cell mitochondria

Glycolysis is an anaerobic process, indicating that the glycolytic reactions

d. require no oxygen.

Consider a gene with two alleles that show complete dominance. When a homozygous recessive individual (qq) is crossed with a heterozygous individual (Qq), they have a 50 percent chance of producing a homozygous recessive offspring. The next time these two individuals breed, what are the chances that they will once again have a homozygous recessive progeny?

d. 50% FEEDBACK: Each reproduction event is the result of the fusion of a single gamete from each of the two parents, and therefore they are independent events. Thus, the probabilities remain the same each time.

Which of the following molecules carries electrons to the electron transport chain of oxidative phosphorylation?

d. NADH

The pedigree shown most likely represents a condition that is

d. autosomal recessive FEEDBACK: The disease shown in this pedigree is most likely autosomal recessive. Individuals of both sexes are equally likely to be affected by autosomal disorders. The disease shown appears to be recessive because it "skips" generations, which indicates some individuals are unaffected carriers. Dominant disorders would appear in each generation.

Which of the following factors might cause a cell to pause in a phase of the cell cycle?

d. damage to DNA FEEDBACK: Cells will not continue through mitosis if their genetic material has been damaged. Damaged DNA that is transmitted to daughter cells may lead to cancer

In the Punnett square shown below, the lettered circles on the top and left of the square (indicated by the arrows) represent the

d. gametes that may be produced by each parent involved in the cross

Cancers are groups of cells that divide rapidly and uncontrollably. Thus, cancer cells

d. have a relatively short G1 pahse

Which of the following is an example of incomplete dominance?

d. heterozygote cat has a medium-sized body instead of being either large or small FEEDBACK: Incomplete dominance occurs when neither allele is fully expressed. Heterozygotes will show an intermediate phenotype.

If a person has two different alleles for a given gene, the person is ________ for that gene.

d. heterozygous FEEDBACK: Individuals with two different alleles are heterozygous. Individuals with two copies of the same allele are homozygous.

A pool of cells is treated with a chemical that halts progress through the cell cycle. In which stage of the cell cycle would most cells be found?

d. interphase

Most traits in humans are controlled by the action of multiple genes. These traits are referred to as

d. polygenic FEEDBACK: Traits are often not simple Mendelian traits with a single-gene, single-phenotype pattern of inheritance and expression. More commonly, patterns of inheritance are polygenic, meaning they are controlled by the actions of multiple genes.

A Punnett square is used to

d. predict the genotypes and phenotypes of a genetic cross

Which of the following is true for autosomal recessive alleles associated with a disease?

d. the copies of the allele are required for the individual to be affected FEEDBACK: Autosomal recessive alleles are equally likely to be found in males and females. Two copies of the recessive allele are required for the disease to be seen.