Biology Practice Test

Which nucleotide base is found within DNA but not in RNA?

Thymine. Rationale: The bases adenine, guanine, cytosine, and thymine are found within DNA. In RNA, thymine is replaced with uracil.

Which process synthesizes mRNA using DNA as the template?

Transcription.

Which of the following descriptions relates to water's property of cohesion?

Water beading together on top of a freshly waxed car.

How do large bodies of water moderate climate?

Water stabilizes climate due to its high specific heat.

Which molecule contains the stop codon?

mRNA

If an individual who is homozygous dominant for a given trait is crossed with an individual who is homozygous recessive for the same trait, what percentage of offspring should show the recessive phenotype? Assume a simple dominance inheritance pattern.

0% Rationale: Because the homozygous dominant individual can only provide the dominant allele to its offspring, all of the offspring will have the dominant allele and express the dominant phenotype. Thus, none of the offspring would show the recessive phenotype.

What is the function of tRNA during translation?

tRNA brings the correct amino acids to the site of synthesis in the ribosome.

Consider a cell undergoing meiosis. Which best describes the cells resulting from meiosis I?

2 haploid cells with each chromosome composed of 2 sister chromatids

How many pairs of autosomes do humans have?

22

For every glucose molecule that undergoes cellular respiration, approximately how many ATP molecules can be produced?

32-36

What is the product of meiosis?

4 genetically different haploid cells

Consider the cell cycle. If a cell has 10 picograms of DNA during G2 phase, how much DNA does it have during G1 phase?

5 picogram

Which of the following properties is responsible for the passing of water through a planet? A. Cohesion B. Adhesion C. Osmosis D. Evaporation

A. Cohesion. Rationale: The property of cohesion is responsible for the passage of water through a plant. Cohesion is the attractive force between two molecules of the same substance. The water in the roots of the plant is drawn upward into the stem, leaves, and flowers by the presence of other water molecules. Adhesion is the attractive force between molecules of different substances. Osmosis is a process in which water diffuses through a selectively permeable membrane. Evaporation is the conversion of water from a liquid to a gas.

Which of the following is the most general taxonomic category? A. Kingdom B. Phylum C. Genus D. Order

A. Kingdom. Rationale: Kingdom is the largest, most expansive taxonomic category. A genius is a group of related species, which are capable of breeding and producing smaller offspring. In binominal nomenclature, genus is the first name. An order is any group of similar families. A phylum is a group of closely related classes. The HESI exams requires you to know the name and relative specificity of each taxonomic category. They are listed here in order from most general to most specific: kingdom, phylum, class, order, family, genius, and species.

Which of the following forms of water is the densest? A. Liquid B. Steam C. Ice D. All forms of water have the same density.

A. Liquid. Rationale: Water can exist in three states, depending on temperature. Ranging from coldest to hottest, these states are solid, liquid, and gaseous- or ice, water and steam. Water freezes at zero degrees Celsius. Although the solidity of ice might lead one to believe it is the densest form of water, water actually expands about 9% when it's frozen. This is the reason ice will float in water. Steam is the least dense form of water.

Which of the following is not found within a bacterial cell? A. Mitochondria B. DNA C. Vesicles D. Ribosomes

A. Mitochondria. Rationale: Bacteria are prokaryotes composed of single cells; their cell walls contain peptidoglycans. The functions normally performed in the mitochondria are performed in the cell membrane of the bacterial cell. DNA is in the nucleic acid that contains the genetic information of the organism. It is in the shape of a double helix. DNA can reproduce itself and can synthesize RNA. A vesicle is a small cavity containing fluid. A ribosome is a tiny particle composed of RNA and protein, in which polypeptides are constructed.

What is the name for the physical presentation of an organism's genes? A. Phenotype B. Species C. Phylum D. Genotype

A. Phenotype. Rationale: A phenotype is the physical characteristics of the organism. Phenotype is often contrasted with genotype, the genetic makeup of an organism. The genotype of an organism is not visible in its presentation, phylum is a group of classes that are closely relates. A species is a group of like organisms that are capable of breeding together and producing similar offspring.

What is the second part of an organism's scientific name? A. Species B. Phylum C. Population D. Kingdom

A. Species. Rationale: The second part of an organism's scientific name is its species. The system of naming species is called binomial nomenclature. The first name is the genus, and the second name is the species. In binomial nomenclature, species is the specific designation. This system enables the same name to be used all around the world, so that scientists can communicate with one another. Genus and species are just two of the categories in biological classification, otherwise known as taxonomy. The levels of classification from most general to most specific, are kingdom, phylum, class, order, family, genus, and species. As you can see, bionomical nomenclature only includes the two most specific categories.

What is the typical result of mitosis in humans? A. Two diploid cells B. Two haploid cells C. Four diploid cells D. Four haploid cells

A. Two diploid cells Rationale: Mitosis is the division of a body cell into two daughter cells. Each of the two produced cells has the same set of chromosomes as the parent. A diploid cell contains both sets of homologous chromosomes. A haploid cell contains only one set of chromosomes, which means that it only has a single set of genes.

Which of the following is necessary for cell diffusion? A. Water B. Membrane C. ATP D. Gradient

A. Water. Rationale: Diffusion is the movement of molecules from an area of higher concentration to lower concentration. This process takes place in the body in a number of different areas. For instance, nutrients diffuse from partially digested food through the walls of the intestines into the bloodstream. Similarly, oxygen that enters the lungs diffuses into the bloodstream through membranes at the end of the alveoli. In all these cases, the body has evolved special membranes that only allow certain materials through.

The alternate versions of a single gene are known as:

Alleles.

During which phase of mitosis do sister chromatids separate?

Anaphase.

Which of the following is a protein? A. Cellulose B. Hemoglobin C. Estrogen D. ATP

B. Hemoglobin. Rationale: Proteins contain carbon, nitrogen, oxygen, and hydrogen. These substances are required for the growth and repair of tissue and the formation of enzymes. Hemoglobin is found in red blood cells and contains iron. It is responsible for carrying oxygen from the lungs to the various body tissues. Adenosine triphosphate (APT) is a compound used by a living organisms to store and use energy. Estrogen is a steroid hormone that stimulates the development of female sex characteristics. Cellulose is a complex carbohydrate that composes the better part of the cell wall.

What is the longest phase in the life of a cell? A. Prophase B. Interphase C. Anaphase D. Metaphase

B. Interphase. Rationale: Interphase occurs between cell divisions. Prophase is the initial stage of mitosis. It is also the longest stage. During prophase, the chromosomes become visible, and the centrioles divide and position themselves on either side of the nucleus. Anaphase is the third phase of mitosis, in which chromosome pairs divide and take up positions on opposing poles. Metaphase is the second stage in mitosis. In it, the chromosome align themselves across the center of the cell.

Which of the following is not a product of the Krebs cycle? A. Carbon dioxide B. Oxygen C. Adenosine triphosphate (ATP) D. Energy carriers

B. Oxygen. Rationale: Oxygen is not one of the products of the Krebs cycle. The Krebs cycle is the second stage of cellular respiration. In this stage, a sequence of reactions converts pyruvic acid into carbon dioxide. This stage of cellular respiration produces the phosphate compounds that provide most of the energy for the cell. The Krebs cycle is also known as the citric acid cycle or the tricarboxylic acid cycle.

Which of the following cell types has no nucleus? A. Platelet B. Red blood cell C. White blood cell D. Phagocyte

B. Red blood cell. Rationale: RBC's do not have a nucleus. These cells are shaped a little like a doughnut, although the cole in the center is not quite open. The other three types of cell have a nucleus. Platelets, which are fragments of cells and are released by the bone marrow, contribute to blood clotting. WBC's, otherwise known as leukocytes, help the body fight disease. A phagocyte is a cell that can entirely surround bacteria and other microorganisms. The two most common phagocytes are neutrophils and monocytes, both of which are WBC's.

How are lipids different than other organic molecules? A. They are indivisible. B. They are not water soluble. C. They contain zinc. D. They form long proteins.

B. They are not water soluble. Rationale: Unlike other organic molecules, lipids are not water soluble. Lipids are typically composed of carbon and hydrogen. Three common types of lipids are fats, waxes, and oils. Indeed, lipids usually feel oily when you touch them. All living cells are primarily composed of lipids, carbohydrates, and proteins. Some examples of fats are lard, corn oil, and butter. Some examples of waxes are beeswax and carnauba wax. Some examples of steroids are cholesterol and ergosterol.

How does water affect the temperature of a living thing? A. Water increases temperature. B. Water keeps temperature stable. C. Water decreases temperature. D. Water does not affect your temperature.

B. Water keeps temperature stable. Rationale: Water stabilizes the temperature of living things. The ability of warm-blooded animals, including humans beings, to maintain a constant internal temperature is known as homeostasis. Homeostasis depends on the presence of water in the body. Water tends to minimize changes in temperature because it takes a while to heat up or cool down. When the human body gets warm, the blood vessels dilate and blood moves away from the torso and toward the extremities. When the body gets cold, blood concentrates in the torso. This is the reason why hands and feet tend to get especially cod in cold water.

If an organism is AaBb, which of the following combinations in the gametes is impossible? A. AB B. aa C. aB D. Ab

B. aa Rationale: It is impossible for each letter to be used more than one time, so it would be impossible for the lowercase a to appear twice in the gametes. It would be possible, however, for Aa to appear in the gametes, since there is one uppercase A and one lowercase a. Gametes are the cells involved in sexual reproduction. They are germ cells.

Which type of organism is a prokaryote?

Bacteria

What kind of bond connects sugar and phosphate in DNA? A. Hydrogen B. Ionic C. Covalent D. Overt

C. Covalent. Rationale: The sugar and phosphate in DNA are connected by covalent bonds. A covalent bond is formed when atoms share electrons. It is very common for atoms to share pairs of electrons. An ionic bond is created when one or more electrons are transferred between atoms. ionic bonds, also known as electrovalent bonds, are formed between ions with opposite charges. There is no such thing as an overt bond in chemistry.

How many different types of nucleotides are there in DNA? A. One B. Two C. Four D. Eight

C. Four. Rationale: Nucleotides are monomers for nucleic acids, composed of five-carbon sugars, a phosphate group, and a nitrogenous base. Nucleotides make up both DNA and RNA. They are essential for the recording of an organism's genetic information, which guides the actions of the various cells of the body. Nucleotides are also a crucial component of adenosine triphosphate (ATP), one of the parts of DNA and a chemical that enables metabolism and muscle contractions.

Which hormone is produced by the pineal gland? A. Insulin B. Testosterone C. Melatonin D. Epinephrine

C. Melatonin. Rationale: Melatonin is produced by the pineal gland. One of the primary functions of melatonin is regulation of the circadian cycle, which is the rhythm of sleep and wakefulness. Insulin helps regulate the amount of glucose in the blood. Without insulin, the body is unable to convert blood sugar into energy. Testosterone is the main hormones produced by the testes; it is responsible for the development of adult male sex characteristics. Epinephrine, also known as adrenaline, performs a number of functions; it quickens and strengthens the heartbeat and dilates the bronchioles. Epinephrine is one of the hormones secreted when the body senses danger.

What is the name for a cell that does not contain a nucleus? A. Eukaryote B. Bacteria C. Prokaryote D. Cancer

C. Prokaryote. Rationale: A prokaryote is a single-celled organism without a nucleus. It is difficult to identify structures of a prokaryotic cell, even with a microscope. These cells are usually shaped like a rod, a sphere, or spiral. A eukaryote is an organism containing a nuclei. Bacterial cells are prokaryotes, but since there are other kinds of prokaryotes, bacteria cannot be the correct answer to this question. Cancer cells are malignant, atypical cells that reproduce to the detriment of the organism in which they are located.

What is the name of the organelle that organizes protein synthesis? A. Mitochondria B. Nucleus C. Ribosome D. Vacuole

C. Ribosomes Rationale: A ribosome, composed of RNA and protein, is a tiny structure responsible for putting proteins together. The mitochondria converts chemical energy into a form that is more useful for the functions of the cell. The nucleus is the central structure of the cell. It contains the DNA and administrates the functions of the cell. The vacuole is a cell organelle in which useful materials (ex: carbohydrates, salts, water, and proteins) are stored.

Which of the following is the chemical formula for a carbohydrate composed of 12 carbons?

C12H24O12

Which of the following is a reactant of photosynthesis?

CO2

What are the products of the Krebs cycle?

CO2, ATP, NADH. Rationale: The Krebs cycle breaks down pyruvate fully to CO2, producing energy in the form of ATPs and NADH (and FADH2). Glycolysis breaks down glucose to produce NADH, ATP, and pyruvate. The passage of electrons through the electron transport chain results in the formation of H2O and ATP. Photosynthesis results in the formation of O2 and glucose.

During which photosynthetic process is CO2 fixed into organic carbon?

Calvin cycle

Which of the following activities does NOT lead to ATP production?

Calvin cycle.

What is the correct description of metaphase during mitosis?

Chromosomes align along the center of the cell. Rationale: During metaphase, the chromosomes align along the center of the cell. During prophase, chromosomes condense, and the nuclear envelope disappears during prometaphase. Anaphase is when the chromosomes start to separate from each other. Telophase is when the chromosomes gather on either side of the now dividing cell; it is followed by cytokinesis.

What property allows refers to the ability of water molecules to stick to each other?

Cohesion

Which of the following structures is not involved in translation? A. tRNA B. mRNA C. Ribosome D. DNA

D. DNA. Rationale: Translation is the process by which messenger RNA (mRNA) messages are decoded into polypeptide chains. Transfer RNA (tRNA) is a molecule that moves amino acids into the ribosomes during the synthesis of a protein. Messenger RNA carries sets of instructions for the conversion of amino acids into proteins from the RNA to the other parts of the cell. Ribosomes are the tiny particles in the cell where proteins are put together. Ribosomes are composed of ribonucleic acid (RNA) and protein.

Which part of the aerobic respiration uses oxygen? A. Osmosis B. Krebs cycle C. Glycolysis D. Electron transport system

D. Electron transport chain. Rationale: The electron transport enacted during aerobic respiration requires oxygen. This is the last component of biological oxidation. Osmosis is the movement of fluid from an area of high concentration through a partially permeable membrane to an area of lower concentration. This process usually stops when the concentration is the same on either side of the membrane. Glycolysis is the initial step in the release of glucose energy. The Krebs cycle is the last phase of the process in which cells convert food into energy. It is during this stage that carbon dioxide is produced and hydrogen is extracted from molecules of carbon.

What is the name of the process by which a bacterial cell splits into two new cells? A. Mitosis B. Meiosis C. Replication D. Fission

D. Fission. Rationale: Fission is the process of bacterial cell splitting into two new cells. Fission is a form of asexual reproduction in which an organism divides into two components; each of these two parts will develop into distinct organism. The two cells, known as daughter cells, are identical. Mitosis, on the other hand, is the part of eukaryotic cell division in which the cell nucleus divides. In meiosis, the homologous chromosomes in a diploid cell separate, reducing the number of chromosomes in each cell by half. In replication, a cell created duplicate copies of DNA.

Which of the following is not a steroid? A. Cholesterol B. Estrogen C. Testosterone D. Hemoglobin

D. Hemoglobin. Rationale: Hemoglobin is not a steroid, it is a protein that helps to move oxygen from the lungs to various body tissues. Steroids can be either synthetic chemicals used to reduce swelling and inflammation or sex hormones produced by the body. Cholesterol is the most abundant steroid in the human body. It is necessary for the creation of bile, though it can be dangerous if the levels in the body become too high. Estrogen is a female steroid produced by the ovaries (in females), testes (in males), placenta, and adrenal cortex. It contributes to adolescent sexual development, menstruations, mood, lactation, and aging. Testosterone is the main hormones produced by the tests; it is responsible for the development of adult male sex characteristics.

During which phase is the chromosome number reduced from diploid to haploid? A. S phase B. Interphase C. Mitosis D. Meiosis I

D. Meiosis I Rationale: During meiosis I, the chromosome number is reduced from diploid to haploid. Interphase is the period of the cell cycle that occurs in between divisions of the cell. In meiosis, the homologous chromosomes in a diploid separate, reducing the number of chromosomes in each cell by half. Mitosis is the phase of cell division in which the cell nucleus divides. S phase is the part of the mitotic cycle in which DNA is synthesized.

During which step of cellular respiration is NADH oxidized to produce ATP and water?

Electron transport chain.

Which of the following are produced as a result of photosynthesis?

Glucose and oxygen.

Glycolysis is the conversion of _______ to ______ .

Glucose, pyruvate.

The first step in the breakdown of glucose to extract energy for cellular metabolism is __________.

Glycolysis

Which part of cellular respiration takes place in the cytosol of the eukaryotic cell?

Glycolysis

What term refers to 2 chromosomes that have the same genes in the same order but not necessarily the same alleles of each gene?

Homologous

What type of bond forms between water molecules that allows them to stick to each other?

Hydrogen

A statement or explanation of certain events is called a(n):

Hypothesis.

Which statement describes the relationship between the densities of ice and liquid water?

Ice has a lower density than liquid water.

Where is the electron transport chain located in a eukaryotic cell?

Inner mitochondrial membrane

What type of molecule are hormones like testosterone and estrogen?

Lipids

Which of the following is an example of an anabolic pathway?

Making a protein from amino acids.

Which organelle is responsible for cellular respiration?

Mitochondria

Which organelle likely arose as a result of the endosymbiosis of a bacterium inside of a primitive eukaryotic cell?

Mitochondrion

Which of the following processes begins with a diploid cell and ends in the formation of diploid cells?

Mitosis only. Rationale: Mitosis makes two identical daughter cells from an original parent cell and does not reduce chromosome content. Meiosis is a process that begins with a diploid cell and results in the formation of haploid cells.

Which of the following statements is CORRECT about daughter cells formed during mitotic cell division?

Mitosis results in two identical daughter cells to their parent cell.

Which list has the levels of biological organization correctly ordered from smallest to largest?

Molecule, Organelle, Cell, Tissue, Organ, Organism, Population, Community, Ecosystem

Which parts of two complementary nucleotides interact with each other in a double-stranded DNA molecule?

Nitrogenous bases.

Where does transcription occur in a eukaryotic cell?

Nucleus

Where are the two places ribosomes can be found inside of a eukaryote cell?

On the rough endoplasmic reticulum and in the cytoplasm.

Which of the following is a way to visualize a family's history, indicating which individuals had a particular genetic trait?

Pedigree

Which term refers to when one gene influences multiple seemingly unrelated phenotypic traits?

Pleiotropy Rationale: Pleiotropy refers to when one gene influences multiple seemingly unrelated phenotypic traits. Simple dominance refers to when being either homozygous dominant or heterozygous results in the individual having the same dominant phenotype. Epistasis refers to an situation where two or more genes interact whereby the genotype at one gene influences the expression of the genotype at another allele. Polygenic inheritance refers to when one phenotypic trait is influenced by multiple genes.

What kind of bond is formed with atoms in a water molecule?

Polar covalent.

Which level of biological organization is the smallest unit that can evolve?

Population

When does exchange of genetic information between non-sister chromatids within a duplicated homologous chromosome pair occur?

Prophase I of meiosis

What is the largest type of biological molecule?

Proteins.

What type of biological molecules are enzymes?

Proteins.

Which level of protein structure refers to the association of the various subunits of a multi-subunited protein into a three-dimensional functional protein

Quaternary

Which cellular structure is found in both prokaryotes and eukaryotes?

Ribosomes.

During which phase of the eukaryotic cell cycle is DNA replicated?

S phase. Rationale: The G1, S, and G2 phases are all phases within interphase. S phase is when DNA is replicated. The G1 and G2 phases are periods of cell growth (G1 = first growth phase, G2 = second growth phase and preparation for division). M phase includes mitosis and cytokinesis.

What is the difference between saturated and unsaturated fatty acids?

Saturated fatty acids contain no double bonds, unlike unsaturated fatty acids.

What component of animal fats cause them to solidify at room temperature?

Saturated fatty acids.

The liver is an organ responsible for detoxifying the body of many harmful substances. Therefore, you might expect liver cells to each contain a high amount of:

Smooth endoplasmic reticulum.

Which of these defines specific heat?

The amount of heat needed to raise the temperature of one gram of a substance by one degree celsius.

Which best describes the light reactions of photosynthesis?

The light reactions convert solar energy to chemical energy through making ATP.

Which statement best describes the hydrophobic part of a cell membrane?

The membrane interior composed of fatty acids

Which of the following correctly compares the molecular orientation of molecules in liquid versus solid water (ice)?

The water molecules are more spread out in ice than they are in liquid water.