Part 3 EOC Review

MOLECULAR AND CELLULAR BIOLOGY (35% OF TEST)

SC.912.L.18.1 Macromolecules

Multiple Choice

As food travels through the digestive system, it is exposed to a variety of pH levels. The stomach has a pH of 2 due to the presence of hydrochloride acid (HCl), and the small intestine has a pH ranging from 7 to 9. HCl converts pepsinogen into pepsin, an enzyme that digests proteins in the stomach. Which of the following most likely happens to pepsin as it enters the small intestine?

• A. It becomes inactive.

• B. It begins to replicate.

• C. It's shape changes to engulf large proteins.

• D. It's activity increases to digest more proteins.

Explanation

Enzymes have an ideal pH, at which they best function. Many enzymes cannot function at all outside their ideal pH range. Pepsin functions best in the extreme acid environment of the stomach and will, therefore cease to function in the much higher pH of the small intestine.

Multiple Choice

In living cells, enzymes act as catalysts, which may reduce the amount of activation energy required for a chemical reaction to occur. In the graphs below, pathway x is a solid line representing the uncatalyzed reaction. The dotted line shows the catalyzed reaction. Which graph best illustrates the changes in a reaction when the catalyst reduces the amount of energy required?

• A

• B

• C

• D

Explanation

A catalyst decreases the activation energy needed for a reaction to occur. This allows the reaction to happen faster. 

Multiple Choice

The diagram below shows the general structure of an amino acid. Which type of molecule is formed from amino acids?

• A. lipids

• B. proteins

• C. carbohydrates

• D. nucleic acids

Explanation

Proteins are long chains of amino acids folded into specific shapes, which determine their properties and reactivity. 

Multiple Choice

You are analyzing a compound in the laboratory. You find that it is made up of carbon, hydrogen, and oxygen in a ratio of two hydrogen atoms for each carbon atom. How will you classify the compound?

• A. lipid

• B. protein

• C. carbohydrate

• D. nucleic acid

Explanation

Carbohydrates are made up of Carbon, hydrogen, and oxygen. See the video for the basic carbohydrate structure. 

Multiple Choice

Fats, oils and cholesterol are all types of what?

• A. cell membranes

• B. hormones

• C. lipids

• D. fatty acids

See the structure of lipids in the video.

Multiple Choice

RNA and DNA are which type of macromolecules?

• A. carbohydrate

• B. lipid

• C. nucleic acid

• D. protein

Explanation

DNA is deoxyribonucleic acid and RNA is ribonucleic acid.

Multiple Choice

What will most likely happen if an appropriate enzyme is added to a chemical reaction?

• A. The reaction rate will increase.

• B. The equilibrium of the reaction will be maintained.

• C. The reaction rate will decrease.

• D. The reaction will stop

Explanation

Enzymes are molecules that increase the rate of reactions. 

Multiple Choice

A sugar, a phosphate group, and a nitrogen base form the building blocks of which organic compound?

• A. carbohydrates

• B. lipids

• C. nucleic acids

• D. proteins

See the video for the basic structure of nucleic acids

Multiple Choice

The human body maintains a temperature of around 98.6 degrees at all times. Enzymes are involved in almost every chemical reaction in the body. Which of the following describes the connection between these two statements?

• A. Enzymes function best at a specific temperature.

• B. The body needs to be warm to prevent hypothermia.

• C. The body is kept relatively warm to prevent too much enzyme action.

• D. There is no connection between the two statements.

Explanation

Enzyme activity is affected by temperature. Each enzyme has a specific temperature range in which it works most effectively. Most biological enzymes present in the human body have an ideal temperature range of around 98.6 degrees. 

Multiple Choice

The enzyme lactase will break down the sugar lactose into which of the following components?

• A. monosaccharides

• B. nucleic acids

• C. amino acids

• D. phospholipids

Explanation

Sugars are made of building blocks called monosaccharides. 

SC.912.L.16.3 DNA Replication

Multiple Choice

Genes for medically important proteins can be cloned and inserted into bacteria, as shown in the diagram below.Why can bacteria recognize a human gene and then produce a human protein?

• A. DNA replication in bacteria and humans is the same.

• B. Bacterial cells contain the same organelles as human cells.

• C. The basic components of DNA are the same in humans and bacteria.

• D. Bacterial cells and human cells contain the same kind of chromosomes.

Explanation

Actually, the basic components of DNA are the same in ALL living things. 

Multiple Choice

Which choice describes DNA after replication has taken place?

• A. one molecule with two original strands and one molecule with two new strands

• B. two molecules, each with one original and one new strand

• C. two molecules, each with two new strands

• D. two molecules, each with two old strands

Explanation

DNA separates into two strands during replication. Each original strand is used to make one complimentary new strand. 

Multiple Choice

At what point in the cell cycle does DNA replication occur and why?

• A. before a cell divides, to provide each of the two resulting cells with a complete set of DNA instructions

• B. before a cell divides, to ensure that the DNA will fit into the resulting cells

• C. during cell division, to ensure that the DNA will fit into the resulting cells

• D. after a cell divides, to provide each of the two resulting cells with a complete set of DNA instructions

Explanation

During mitosis, everything in the original cell must make a copy of itself so that the two daughter cells have as much DNA and chromosomes as the original. 

Multiple Choice

Four different segments of a DNA molecule are represented below.There is an error in the DNA in which molecule?

• A. segment 1 only

• B. segment 3 only

• C. segment 2 and 3

• D. segment 2 and 4

Explanation

In segment 3, Adenine is improperly paired with Cytosine. Adenine should be paired with Thymine, and Cytosine should be paired with Guanine in DNA. 

Multiple Choice

The sequence of DNA below is part of a gene. How many amino acids are coded for by this segment?

5' ATCAGCGCTGGC 3'

• A. 4

• B. 8

• C. 12

• D. 20

Explanation

Each section of three nucleotides (called a triad) codes for one amino acid. Since there are four triads here, this piece of DNA codes for 4 amino acids

Multiple Choice

A scientist puts nucleotide chains of UUUUUU in a test tube under conditions allowing protein synthesis. Soon the test tube is full of polypeptide chains composed only one the amino acid phenylalanine. What does this experiment indicate?

• A. The amino acid phenylalanine is composed of uracil

• B. UUU codes for the amino acid phenylalanine

• C. Protein synthesis malfunctions in test tubes.

• D. Most proteins contain only one type of amino acid

Explanation

UUU coded for the amino acid phenylalanine to be created (synthesized) in the test tube. Each three DNA nucleotides codes for one amino acid. 

Multiple Choice

Which of the following would most likely cause a mutation?

• A. the placement of ribosomes on the endoplasmic reticulum

• B. the insertion of a nucleotide into DNA

• C. the movement of transfer RNA out of the nucleus

• D. the release of messenger RNA from DNA

Explanation

Mutations are caused by changes in the DNA sequence. The insertion of just one nucleotide would change the sequence and alter the amino acids that are coded from that particular piece of DNA. 

Multiple Choice

A diagram of a cellular process is shown below. Which of the following identifies the process shown at point Z?

• A. Translation

• B. Translocation

• C. Replication

• D. Transcription

Explanation

Translation is the process of the ribosomes reading messenger RNA (mRNA) and forming polypeptide chains with the correct sequence of amino acids. 

Multiple Choice

During transcription the DNA base sequence is transcribed into a complimentary mRNA sequence. A codon table like the one shown below lists the amino acids coded for by particular triads of mRNA bases. A segment of DNA has undergone a mutation in which one nucleotide has been changed. The original sequence was ACG and the new sequence is ACA. Use the codon table to determine whether or not this mutation will cause a change in the phenotype of the organism.

• A. yes, the phenotype of the organism would change because a new amino acid will be coded for

• B. yes, the phenotype of the organism would change because any change in the DNA sequence will cause a change in phenotype

• C. Even though the DNA sequence changed, the sequence still codes for the same amino acid, so no change in phenotype will occur.

• D. It is impossible to determine if a change in phenotype will occur using only the DNA sequence.

Explanation

ACG and ACA both code for the amino acid Thr so no phenotypic change will occur.

Multiple Choice

Which of the following carries amino acids to the site of protein synthesis?

• A. mRNA

• B. rRNA

• C. tRNA

• D. nRNA

Explanation

tRNA, or transfer RNA carries proteins to the ribosomes to be connected into polypeptide chains. mRNA carries the genetic code out of the nucleus and to the ribosomes. rRNA is what ribosomes are made of

SC.912.L.16.17 Mitosis and Meiosis

Multiple Choice

Mitosis and meiosis are processes involved in cellular reproduction. Which of the following describes and event that results from mitosis but NOT meiosis?

• A. two stages of cell division

• B. replication of cellular genetic material

• C. daughter cells that are identical to the parent cell

• D. four daughter cells that are produced from each parent cell

Explanation

Mitosis is the process of cell division for all cells in the body except reproductive cells. Mitosis results in daughter cells that are identical to the parent cell in every way including number of chromosomes. 

Multiple Choice

How are sexual reproduction and asexual reproduction different from each other?

• A. sexual reproduction requires two parents and asexual reproduction requires only one parent

• B. asexual reproduction requires two parents and sexual reproduction requires only one parent

• C. mutation rates are lower in sexual reproduction than in asexual reproduction

• D. asexual reproduction occurs only in multicellular organisms

Explanation

During sexual reproduction, genetic information from two organisms is combined. This results in genetic variation in the population. 

Multiple Choice

Which type of reproduction leads to increased genetic variation on a population?

• A. Parthenogenesis

• B. asexual reproduction

• C. Sexual reproduction

• D. Vegetative reproduction

Explanation

During sexual reproduction, the genetic information from each parent is combined and reorganized to provide a unique new individual. This process introduces genetic variation into a population.

Multiple Choice

Which of the following phrases best describes cancer?

• A. absence of cyclins in the DNA

• B. miltiple gene mutations on a chromosome of DNA

• C. uncontrolled cell growth caused by mutations in genes that control the cell cycle

• D. presence of genetic defects caused by hereditary disorders

Explanation

Cancer cells lack the ability to recognize and control cell growth and reproduction. As a result, they replicate again and again. 

Multiple Choice

Which of the following phases of mitosis is represented by the diagram below?

• A. prophase

• B. metaphase

• C. anaphase

• D. telophase

Explanation

During metaphase, chromosomes line up in the center of the cell and prepare to be pulled apart at the centromere. 

Multiple Choice

A scientist wants to change the DNA of a sexually reproducing organism and have the new DNA present in every cell of the organism. In order to do this after fertilization, she would change the DNA in which of the following?

• A. zygote

• B. placenta

• C. testes of the father

• D. ovaries of the mothe

Explanation

The zygote is the first single cell of an organism. The DNA that is present in the zygote will be replicated each time the cell goes through mitosis. 

Multiple Choice

Which row in the chart below indicates the correct process for each event indicated?

• A. row 1

• B. row 2

• C. row 3

• D. row 4

Explanation

The formation of eggs and sperm is a meiotic process resulting in daughter cells that have half of the genetic information of the parent cell. The growth of the embryo is a mitotic process resulting in daughter cells that are identical to the parent cell.

Multiple Choice

The diagram below shows a cellular process that occurs in organisms.What is the name of this process?

• A. meiosis

• B. mitosis

• C. endocytosis

• D. phagocytosis

Explanation

In meiosis a diploid cell, containing two of each chromosome divides to create haploid daughter cells that have one of each chromosome. 

Multiple Choice

The diagram below shows homologous chromosomes during prophase I of meiosis.

Which of the following correctly describes the process being illustrated?

• A. mutation in which the DNA content of the gene is altered

• B. segregation of sister chromatids

• C. condensation and segregation of alleles

• D. crossing-over in which alleles are exchanged

Explanation

This process allows each chromosome to have genetic information from both parents, no matter which parent the chromosome originally came from. Crossing-over is responsible for offspring having some qualities of each parent and is also responsible for genetic variation in a population of species. 

Multiple Choice

Which of the following best describes meiosis?

• A. It is carried out in all tissues that require cell replacement.

• B. It occurs only in cells in the reproductive structures of organisms.

• C. It happens in all tissues except the brain and spinal cord.

• D. It is the first stage of mitosis.

Explanation

Meiosis only occurs in the reproductive cells, producing gametes with half of the genetic information as the parent cell. 

Multiple Choice

The diagram below shows two strawberry plants.Plant 2 is produced asexually from Plant 1. If the leaf cells of Plant 1 have 56 chromosomes, how many chromosomes will be found in the leaf cells of Plant 2?

• A. 14

• B. 28

• C. 56

• D. 112

Explanation

Asexual reproduction results in an identical organism to the parent. All of the cells of the daughter organism will be the same as the cells of the parent organism. Asexual reproduction DOES NOT increase the variation in a population since all of the organisms are genetically identical.