Biology Exam

If 35% of an organism's DNA is thymine, what is the percentage of guanine?

15%

Anaphase

Begins when sister chromatids suddenly separate and begin to move apart. Once this phase begins, each sister chromatid is now considered an individual chromosome. During this phase, the chromosomes separate and move along spindle fibers to opposite ends of the cell. This movement requires the rapid disassembly of microtubules as chromosomes move toward the poles of the mitotic spindle. This phase comes to an end when this movement stops and the chromosomes are completely separated into two groups. The microtubules that once made up the mitotic spindle have almost completely disassembled by the end of this phase.

The sequence of nitrogenous bases on a portion of a strand of DNA is shown in the diagram. From left to right, what is the corresponding sequence of the complementary strand? (G G T G A C T)

C C A C T G A

G1

Cells do most of their growing in this phase. In this phase, cells increase in size and synthesize new proteins and organelles.

__________ is a situation in which the phenotypes produced by both alleles are clearly expressed.

Codominance

Chargaff's rule of base pairing are explained by which structural feature of DNA?

DNA is double-stranded and hydrogens bonds between base pairs hold the strands together.

When does replication take place?

During the S phase of the cell cycle

True or False: Are all mutations bad? Explain. Yes... All mutations produce proteins with new or altered functions that are always harmful to organisms in different or changing environments.

False

True or False: How is DNA replication in a prokaryote different than in a eukaryote? Replication in most prokaryotes starts from dozens of points and proceeds in many directions until the entire chromosome is copied. In eukaryotic cells, replication begins at a single point on the DNA molecule. Then it proceeds in both directions until each chromosome is completely copied.

False

True or False: What is the job of polymerase? The principle enzyme involved in DNA replication. It acts to join Deoxyribose sugar into the DNA polymer. DNA polymerase joins nucleotides to synthesize a new complementary strand of DNA.

False

M phase

In this phase of the cell cycle, which follows interphase, two daughter cells are produced. This phase takes its name from the process of mitosis.

Which conclusion about the genetic code is most strongly supported by the evidence presented in the diagram?

Many amino acids, although not all of them, may be encoded by more than one codon.

A point mutation changes a codon in an mRNA molecule. Will the mutation affect the polypeptide that forms? Why?

Maybe. Some pairs of codons are translated into the same amino acid.

The diagram shows a model of DNA replication. Which of the following labels should NOT be added to the model?

RNA polymerase

What are three ways RNA is different from DNA?

RNA uses the sugar ribose instead of deoxyribose, RNA is generally single stranded, and RNA contains uracil in place of thymine.

Metaphase

The centromeres of the duplicated chromosomes line up across the center of the cell. Spindle fibers connect the centromere of each chromosome to the two poles of the spindle. The cell is now ready to separate those sister chromatids.

Telophase

The chromosomes, which were distinct and condensed, begin to spread out into a tangle of chromatin. A nuclear envelope re-forms around each cluster of chromosomes, and gradually a nucleolus becomes visible in each daughter nucleus.

S phase

The first phase is followed by this phase. During this phase new DNA is synthesized as the chromosomes are replicated. By the end of this phase, the cell contains twice as much DNA as it did at the beginning of the phase.

Prophase

The genetic material inside the nucleus condenses and the duplicated chromosomes become visible. A spindle begins to form outside the nucleus. Each duplicated chromosome condenses to appear as two thick strands known as sister chromatids attached at a point called the centromere. The cell also starts to build a spindle, which is a fanlike system of microtubules that will help to separate the duplicated chromosomes. Spindle fibers extend from a region called the centrosome, where tiny paired structures called centrioles are located. The centrioles move toward opposite ends, or poles, of the cell.

True or False: How does the DNA double helix resemble a twisted ladder? The sugar-phosphate covalent bonded backbones form the sides of the ladder and the nitrogenous bases form the rungs of the ladder.

True

G2 phase

When DNA replication is completed, the cell enters this phase. This phase is usually the shorted of the first three phases. During this phase, many of the organelles and molecules required for cell divisions are produced. When the events of this phase are completed, the cell is ready to enter the next phase and begin the process of cell division.

Meiosis

a process in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell.

What describes the role of the compound with the chemical C6H12O6?

a product that is useful because of its high-energy chemical bonds

What are the four types of nitrogenous bases found in the nucleotides of a DNA molecule?

adenine, guanine, thymine, cytosine

All of the following are sources of energy during exercise EXCEPT...

alcoholic fermentation

Each of the traits Mendel studied was controlled by a singe gene that occurred in two contrasting varieties. These variations produced different expressions, or forms, of each trait. For example, one from of the gene for height produced tall plants and another form produced short plants. The different forms of a single gene are called...

alleles

Natasha is making a model of cellular respiration. Her model shows the pathway followed when there IS enough oxygen available. What does Natasha's model show?

an aerobic pathway consisting of glycolysis, the Krebs cycle, and the electron transport chain

What describes the conversion of ADP to ATP?

an input of energy to attach a third phosphate group

The p53 protein is involved in DNA repair and in triggering cell death when repair is not possible. Why are some cancers associated with defective p53 genes? Select all that apply.

because cells with damaged DNA, p53 protein levels rise and cause apoptosis; because cells with damaged DNA are not triggered to die; because cell growth and division is no longer regulated by p53 protein

Stuart is listing the changes to matter and energy that occur during the process of photosynthesis. What does he need to include in his list?

changes that convert light energy into chemical energy stored in carbohydrates

___________ mutations- chromosomes- changes in the number or structure of chromosomes

chromosomal

________- when one nucleotide is deleted from a DNA molecule

deletion

________- when one part of a chromosome is deleted from the chromosome

deletion

Look at the picture. What does it represent? Choose two correct answers.

differentiation is the process by which cells become specialized; the inner mass of cells of the blastocyst will form the specialized cells in the body

A cell with two sets of homologous chromosomes is said to be _______, meaning double.

diploid

___________- when a part of a chromosome is duplicated and added to a chromosome

duplication

genotype

genetic makeup

The study of biological inheritance is called...

genetics

What are the reactants of cellular respiration?

glucose and oxygen

Xavier and Jill are practicing the 100-meter sprint. Which statement BEST describes the metabolic pathways their muscles will utilize to produce the quick energy needed for this intense exercise?

glycolysis because glucose metabolism, and in the absence of oxygen, lactic acid fermentation takes over

Some cells have a single set of chromosomes and, therefore, a single set of genes. Such cells are _______, meaning single.

haploid

These two sets of chromosomes are __________, meaning that each of the four chromosomes from the male parent has a corresponding chromosome from the female parent.

homologous

Which statement did Chargaff conclude based on this data?

in DNA molecules, [A]=[T], and [C]=[G]

Cases in which one allele is not completely dominate over another are called __________ _________

incomplete dominance

_________- when one nucleotide is inserted into a DNA molecule

insertion

_________- when two parts of a chromosome switch places with each other

inversion

What describes the role of light in the overall process of photosynthesis?

it provides the energy for assembling small molecules into sugars

Xavier is describing the role of electron carriers, such as NADP+, in photosynthesis. What property of NADP+ should Xavier cite?

its ability to accept and release high-energy electrons and a hydrogen ion

Nancy is explaining why chlorophyll is classified as a plant pigment and how it is useful in photosynthesis. What property of chlorophyll would be most appropriate for her to cite?

its reactivity to oxygen

Statistically, the ______ the number of offspring, the closer the results will be to predicted values.

larger

The model includes a wavy arrow to show light striking the thylakoids. Which label for the wavy arrow would be MOST USEFUL for communicating the role of light in photosynthesis?

light is the energy source for converting ADP to ATP, and NADP+ to NADPH

The molecules of RNA that carry copies of these instructions from the DNA molecules in the nucleus to the ribosomes in the cytoplasm are known as...

messenger RNA

Photosynthesis is to chloroplasts as cellular respiration is to

mitochondria

A gene with more than two alleles is said to have ________ _______.

multiple alleles

Lactic acid fermentation occurs in...

muscle cells

What are the three parts of a nucleotide?

nitrogenous base, phosphate group, 5-carbon sugar

The reactions for photosynthesis and cellular respiration are opposite of each other. Select two statements that describe the two processes.

photosynthesis uses carbon dioxide from the atmosphere and produces oxygen; cellular respiration uses oxygen to release energy from food and produces carbon dioxide as a by product

phenotype

physical trait

__________ mutation - nucleotides- occur at a single point in the DNA sequence

point/gene

Traits controlled by two or more genes are said to be _________ ______.

polygenic traits

When analyzing his date, Mendel realized that the principle of ___________ could be used to explain the results of his genetic crosses.

probability

The ____ helps decode the message found on the mRNA.

rRNA

To identify the amino acid sequence encoded by mRNA, which word would be the most useful first step for Robert to follow?

separate the list into three-letter "words"

What structure is found only in prokaryotes?

single, circular DNA in cytoplasm

____________- when one nucleotide takes the place of another DNA molecule

substitution

In a key or legend for the model, how should William describe the roles of NADPH and ATP in the light-independent reactions?

supplying energy necessary to assemble sugar molecules

During the assembly of a protein, a third type of RNA molecule carries amino acids to the ribosome and matches them to the coded mRNA message. These molecules are known as...

tRNA

ATP is produced in all stages of cellular respiration. Which two statements describe the process of ATP synthesis in the electron transport chain?

the ATP synthase spins when the hydrogen ions rush past, acting as a "matchmaker" and grabbing another phosphate group to attach to an ADP molecule; the high concentration of NAD+ acts as a catalyst to speed up the formation of ATP from ADP

What is the role of the anticodon in the process of translation?

the anticodon binds to a codon on mRNA

The diagram shows the structure of a eukaryotic chromosome. Which of the following events is best represented by the diagram?

the binding of DNA by histones

The Krebs cycle consists of many small steps, each catalyzed by an enzyme. What is the another name for the Krebs cycle?

the citric acid cycle

Which of the following happens when cancer occurs?

the control of the cell cycle is impaired

Savannah is asked to explain the locations of cellular respiration. What location should she give for the site of the Krebs cycle reactions?

the matrix of the mitochondria

In the diagram, an arrow leads from the splitting of water, to the two photosystems, and then to NASP+. What process is represented by the arrows?

the movement of electrons along the electron transport chain

6CO2+6H2O --> (light) C6H12O6+O2 Which property of photosynthesis can be identified from this?

the source of carbon atoms in the carbohydrate

Under normal conditions, gases diffuse through small holes in the leaves of a plant. When the weather is very hot and dry, pants may close these openings to conserve water. How are the closures most likely to affect photosynthesis?

they decrease the rate of photosynthesis by preventing carbon dioxide from entering the leaf

What purpose is served by cell division in a multicellular organism? Select all the correct answers.

to ensure that a cell does not become too large; to produce new cells during an organism's growth; to replace damaged cells and tissues

Why do cells divide? Select all that apply.

to ensure that a cell does not become too large; to produce new cells during an organism's growth; to replace damaged cells and tissues

_____________- when a part of one chromosome is added to another chromosome

translocation

In the process of glycolysis, four ATP molecules are synthesized from four ADP molecules. Why does glycolysis not yield four molecules of ATP?

two ATP molecules are required to start the process