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Biology Practice Exam


Try this free biology practice test to study for your biology exam.

Whether you are in high school or college, this biology practice exam will test your knowlege. Biology tests cover such subjects as the chemistry of life, cells, genetics, evolution, protista and monera, fungi, plants, animals and ecology.  When you are done, click the submit button and the exam will be instantly scored with fully explained answers.

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1 The net effect of photosynthesis, chemically, is reduction, leading to the formation of which products?
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The reactants in the process of photosynthesis are carbon dioxide and water. Sunlight is needed for the reactions to occur. The products of photosynthesis are oxygen and glucose, a simple carbohydrate. ATP is used in photosynthesis but is neither a reactant nor a product. ATP is produced in a different process called cellular respiration.

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2 A cell membrane is ______________?
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A cell membrane is a thin layer of molecules that surrounds the cell. Its function is to allow certain materials to enter the cell, yet, keep harmful materials out. In order to do this, the cell controls which substances can enter the cell through the membrane. The cell membrane is selectively permeable (or semipermeable), which means that certain molecules, such as oxygen and water, are permitted to enter the cell. Molecules that are not recognized as helpful are not able to pass through the membrane.
3 A cell uses which of the following to accelerate chemical reactions enabling its metabolic machineryto operate?
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Enzymes are catalysts, chemicals that speed up chemical reactions. The conditions inside mostcells do not allow reactions to proceed quickly enough to support life. For example, temperaturesinside organisms are not hot enough for chemical reactions to take place quickly. Enzymesincrease the rates of biological chemical reactions.
4 Which of the following is not part of the metabolic sequence?
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Inside cells, sequences of chemical reactions take place to support life. These sequences areknown as metabolic pathways. Photosynthesis, respiration, and digestion are all examples ofmetabolic pathways, or sequences. Photosynthesis is the metabolic pathway that produces oxygen and glucose in organisms with chlorophyll. Respiration breaks down molecules called ATP for cells to use as energy. Digestion breaks down food to be used to make energy in the form of ATP. Hydroplasm is not a known metabolic sequence.

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5 Which of the following are NOT organelles found in animal cells?
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Chloroplasts and central vacuole are important organelles in plant cells. Chloroplasts contain chlorophyll and are the site of photosynthesis. Central vacuoles are used to store water in plant cells. All the other organelles listed are important to the function of animal cells and plant cells.
6 Light initiates different types of cellular reactions. Which of the following responses to light converts the energy from light into a gain of potential energy?
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Photosynthesis is the process plant cells use to convert oxygen, water and sunlight into ausable form of energy. The product of photosynthesis is glucose (sugar) molecules. Glucose molecules are a form of potential energy that can be broken down by an organism to produce energy in the form of ATP molecules.
7 The functional unit of heredity is the _____________.
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A gene is the basic unit of heredity. Genes are made of DNA sequences and act as instructions for making proteins (although not all genes make proteins). Genes are found on chromosomes.Chromosomes are located in a cell's nucleus.

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8 DNA exists in the form of __________ strands of DNA coiled about each other.
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DNA is made of two strands of nucleotides (basic units of DNA). The DNA molecule looks likea twisted ladder and is referred to as a double helix. Each nucleotide contains a sugar moleculeand a phosphate group, along with a nitrogen base. The sugar molecules and phosphate groupsmake up the sides of the ladder, and the nitrogen bases make up the "steps" of the ladder.
9 Genes are located within the cytoplasm of the cell.
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Genes are sequences of DNA on a chromosome. All DNA is located inside a cell's nucleus.
10 Genetic information is transferred from the nucleus to cytoplasm by way of _______________.
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Messenger RNA (ribonucleic acid) transfers genetic information from the DNA in a cell's nucleus to ribosomes. In the ribosome, the information coded onto messenger RNA is used to make proteins.

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11 When sexual reproduction occurs in multicellular organisms, a process takes place before cellsfuse whereby a cell is left with half of its chromosomes, enabling the creation of a cell with a characteristic chromosome number. What is this process called?
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During meiosis, gametes (sex cells) are formed by reducing the number of chromosomes found in somatic (body) cells by one half. This occurs so that when two gametes, one from each parent, fuse together, the embryo will contain the correct number of chromosomes. Without meiosis, offspring cells would contain double the number of chromosomes of normal adults and they would not be viable.
12 Which of the following represents the largest group of biological classification?
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Biology uses a system of classification to group organisms together based on their characteristics.The levels of classification, from largest (most inclusive) to smallest (most specific), include domain, kingdom, phylum, class, order, family, genus, species.
13 There are two types of cells, eukaryotic and prokaryotic. Which of the following cellular structures are found in both types of cell?
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Prokaryotic and eukaryotic cells both contain DNA. Prokaryotic cells are found in bacteria and their structure is much more simple than eukaryotic cells. Prokaryotic cells have a few simple cellular structures such as a nucleoid region, ribosomes, and a plasma membrane. Eukaryotic cells have more highly developed cellular structures including organelles that support the function of the cell. Golgi apparatus and mitochondria are found in eukaryotic cells. Chloroplasts are found in eukaryotic cells that contain chlorophyll, such as plants.

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14 What is the name given to specialized structures within cells responsible for carrying out specific functions such as providing energy and producing hormones?
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Organelles are specialized structures in cells that support the cellular functions. For example, mitochondria are organelles that synthesize energy; ribosomes synthesize protein; chloroplasts convert sunlight, carbon dioxide and water into oxygen and sugar.
15 All of the following are similarities between unicellular organisms and multicellular organisms, except _____________.
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Unicellular organisms are very small compared to most multicellular organisms. If they were as large as a multicellular organism, their surface area to volume ratio would be too low to support life. Staying small gives unicellular organisms a high surface area to volume ratio. Surface area to volume ratio refers to the amount of surface area on the outside of the cell compared to the cell's volume. Larger cells have less surface area compared to their volume. Molecules move into the cell, out of the cell and through the cell slowly through the cell membrane. Having a large surface area provides more space for molecules to diffuse across the cell membrane and less of a distance to travel inside the cell to supply organelles with materials needed for metabolism.
16 How many chromosomes does an individual human person have?
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Humans have 46 chromosomes. Each parent contributes 23 chromosomes in a gamete (sex cell). When the gametes combine to form an embryo, the embryo then contains two sets of chromosomes, equal to a total of 46 chromosomes.

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17 A multicellular organism is:
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Multicellular organisms include organisms with more than one eukaryotic cell. Animals and plants are all multicellular. All prokaryotic organisms are unicellular, meaning the entire organism consists of a single cell. There are some unicellular eukaryotic organisms, such as protists and some fungi (yeast).
18 The term thallus refers to the plant-like structure of which of the following organisms?
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Algae bodies that are plantlike, such as the structure of brown algae, are referred to as a thallus. Where plants have roots, stems and leaves, a thallus consists of a hold fast (rootlike part), stipe (stem like part), and blades (leaf like parts).
19 Single-celled protists with animal-like behavior belong to the phylum ______________.
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Organisms in Kingdom Protista include eukaryotes that do not share all of the characteristics of organisms in the kingdoms Animalia, Fungi or Plantae. Within Kingdom Protista are a group of protists that behave like animals. These single-celled organisms are in the Phylum Protozoa.Protozoa include flagellates, ciliates, amoeba and sporozoans.

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20 The bodies of all insects have _______ major divisions.
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The three major body parts of all insects (Class Insecta) are the head, thorax and abdomen. Many animals that are similar in size and appearance are mistaken for insects, such as ticks, mites and spiders. However, these creatures are in the Class Arachnida, not Class Insecta.
21 Sterile female honey bees are called _________________.
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Honey bees live in a colony with a division of labor. The worker bees form the largest group of bees in the hive. They serve many different roles, such as removing dead bees, feeding baby drones, packing pollen, building the honeycomb, and taking care of the queen bee. The queen bee is the only fertile female bee in the colony. Worker bees remain infertile as long as the queen bee is alive.
22 Which of the following organisms is a vertabrate?
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Vertebrates are multicellular organisms in Kingdom Animalia. Vertebrates are animals with a backbone, and include mammals, birds, fish, reptiles and amphibians. Insects, earthworms and sea stars belong to a group of animals without a backbone, invertebrates.

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23 Many animals protect themselves with an exoskeleton. Which of the following is an example of an animal with an exoskeleton?
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Exoskeletons are skeletons located on the outside of an animal's body. They are used for protection and to support the animal. Mollusks and insects are examples of animals with endoskeletons. Birds, turtles and snakes are all animals with endoskeletons. Endoskeletons are internal skeletons. 
24 Locomotion in Metazoa is usually due to the contraction of what?
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Organisms in Kingdom Animalia have muscles and nerves. If an animal can move from one place to another (known as locomotion), it is doing so by contracting its muscles. Not all animals have skin and/or a skeleton.
25 In normal sexual reproduction, two mature gametes fuse to form a(n) _____________.
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Gametes are haploid cells, which means they contain half the number of chromosomes that body cells contain. Gametes are used in sexual reproduction to form an offspring. When two gametes fuse together during sexual reproduction, they form a zygote.

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26 In humans, how do the sex chromosomes differ between males and females?
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In humans, there are two sex chromosomes, referred to as “X” and “Y.” Females have two X chromosomes in each body cell and in each sex cell (gamete). Males have one X chromosome and one Y chromosome. If a person inherits two X chromosomes, one from each parent, that person will develop into a female. If a person inherits an X chromosome from the mother and a Y chromosome from the father, that person will develop into a male.
27 Changes in the genetic makeup of an organism may be due to which of the following?
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There are three ways genetic variation may take place: New combinations of chromosomes result from sexual reproduction; chromosome mutation and gene mutation occur during mitosis and/or meiosis.
28 The phrase "survival of the fittest" is an alternate phrase expressing which of the following principles?
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“Survival of the fittest” is an expression used to describe natural selection. Natural selection takes place when organisms with the characteristics best suited for their environment survive and produce fertile offspring. The “fittest” in the phrase is referring to the organisms that have the characteristics that allow them to survive in their environment. In theory, these organisms will not only survive, but will also reproduce. Their offspring will also have the characteristics that allowed the parent to successfully survive. Over time, these characteristics will continue to be passed on to future generations. Organisms that lack the characteristics to survive will die before reproducing, and therefore, not pass on the less desirable characteristics.

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29 Which of the following directly (as opposed to indirectly) supports Charles Darwin's theory of evolution?
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Genetic evidence is the most direct type of evidence used to support the theory of evolution. Since adaptations are passed along genetically, from one generation to another, evidence for evolution can be collected by examining the genome of individuals of the same species and comparing it to genetic information of ancestral species, species of the same phylogenetic groups and/or common ancestors between several species.
30 ___________ occurs when organisms of different species mate and form offspring.
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Hybridization occurs when individuals of different species mate and form offspring. The offspring are referred to as hybrids. In order for hybridization to occur, the parents must be similar to each other. For example, a horse and a donkey can reproduce to form a mule. However, a fly cannot mate with a bird to create a new organism. When hybridization occurs, the offspring are typically sterile.
31 Which cellular structure is responsible for producing ribosomal RNA and is often called the "factory" of the cell?
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The nucleolus, located within the nucleus, synthesizes ribosomal RNA (rRNA) and assembles ribosomes. It's often referred to as the cellular "factory" because it produces essential components for protein synthesis. While the nucleus plays a role in cellular activities, it doesn't specifically produce rRNA like the nucleolus. The endoplasmic reticulum is a membrane-bound organelle found in eukaryotic cells. It consists of an extensive network of membranes and comes in two forms: rough endoplasmic reticulum (RER), studded with ribosomes on its surface, involved in protein synthesis, and smooth endoplasmic reticulum (SER), which lacks ribosomes and is associated with lipid synthesis, detoxification, and storage of calcium ions. Golgi apparatus further processes and sorts proteins received from the endoplasmic reticulum for transport to their eventual destinations; lysosomes, the plasma membrane, or secretion.

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32 During which phase of the cell cycle does DNA replication occur?
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DNA replication occurs during the Synthesis (S) phase of the cell cycle. This phase is dedicated to the synthesis of DNA, ensuring that each daughter cell receives a complete set of genetic information during cell division. The G1 and G2 phases are critical checkpoints, but they are not specifically associated with DNA replication. Cell division occurs during M phase, which consists of nuclear division followed by cytoplasmic division.
33 In cellular respiration, which stage produces the majority of ATP (adenosine triphosphate)?
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The electron transport chain, the final stage of cellular respiration, produces the majority of ATP. This process involves the movement of electrons through protein complexes, generating the energy required for ATP synthesis. While glycolysis and the Krebs cycle contribute to ATP production, they don't produce as much as the electron transport chain. While fermentation helps regenerate NAD+ and allows glycolysis to continue, it is less efficient in terms of ATP production compared to aerobic respiration, where the electron transport chain produces a significant amount of ATP. Therefore, in the absence of oxygen, cells resort to fermentation to sustain energy production, albeit at a lower efficiency.
34 Which of the following is a function of the smooth endoplasmic reticulum?
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The smooth endoplasmic reticulum is involved in lipid synthesis and detoxification. It produces lipids essential for cell membranes and breaks down drugs and toxins in liver cells. While the rough endoplasmic reticulum is involved in protein synthesis, it is not primarily responsible for lipid synthesis and detoxification.

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35 What is the primary function of the enzyme amylase?
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Amylase is specifically designed to break down carbohydrates, converting starches into simpler sugars. Options a, b, and d describe functions associated with other enzymes or processes, such as lipids, proteins, and nucleic acids, which are not within the primary scope of amylase.
36 Which of the following is a characteristic feature of prokaryotic cells?
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Prokaryotic cells have a single, circular DNA molecule in their nucleoid region. Options a and b describe features associated with eukaryotic cells, and option d is not a characteristic feature of prokaryotic cells.
37 What is the primary function of the hormone insulin in the human body?
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Insulin primarily regulates blood sugar levels by facilitating the uptake of glucose into cells. Options a, c, and d describe functions unrelated to insulin's primary role in glucose regulation, such as growth stimulation, general metabolism control, and immune response enhancement.

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38 Which of the following is a greenhouse gas that plays a crucial role in regulating Earth's temperature?
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Carbon dioxide is a significant greenhouse gas that traps heat in the Earth's atmosphere, contributing to the greenhouse effect. Options a, c, and d, are atmospheric gases but do not have the same impact on regulating temperature as carbon dioxide.
39 What is the process by which plants lose water vapor through small openings in their leaves?
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Transpiration is the specific process of water loss from plants through stomata. Options b, c, and d refer to other plant processes which are distinct from the mechanism of water vapor release during transpiration.
40 What is the term for the movement of molecules from an area of high concentration to an area of low concentration, without the use of energy?
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Passive diffusion is the natural movement of molecules along their concentration gradient without energy input. Active transport, osmosis, and facilitated diffusion involve energy expenditure or specific transport proteins, making them distinct from passive diffusion.

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41 Which of the following is a characteristic of asexual reproduction?
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Asexual reproduction involves the creation of genetically identical offspring without the fusion of gametes. This results in offspring inheriting the exact genetic information from a single parent. Genetic variation, gamete union, and traits from both parents are associated with sexual reproduction, not asexual reproduction.
42 In the scientific classification of living organisms, which category is more specific than "phylum" but more general than "species"?
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In biological classification, "class" is more specific than "phylum" but broader than "order." It serves as an intermediate taxonomic category. "Order," "family," and "genus" are more specific categories than "class," and "species" is the most specific level.
43 Which of the following is a characteristic feature of viruses?
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Viruses lack cellular structures and metabolic machinery, relying on host cells for replication. They contain genetic material (DNA or RNA) but are not cells. Options a and c are incorrect as viruses are not single-celled organisms and lack the ability to carry out independent metabolism. Option b is incorrect as viruses do contain genetic material, albeit simpler than cellular genomes.

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44 In genetics, what term describes the expression of an individual's genetic makeup?
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Phenotype refers to the observable traits that result from the interaction of an individual's genetic makeup (genotype) with environmental influences. It encompasses the physical, biochemical, and behavioral characteristics that can be observed or measured. Options a, c, and d are related to specific genetic components but do not directly describe the expressed traits, making them incorrect in the context of describing the observable characteristics of an individual.
45 What is the primary function of the kidneys in the human body?
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The kidneys play a crucial role in filtering blood, removing waste products, and maintaining fluid and electrolyte balance. This function ensures the body's internal environment remains within optimal conditions. Options a, c, and d describe functions unrelated to the primary role of the kidneys. The kidneys are not involved in the regulation of body temperature, production of red blood cells, or digestion of food.
46 What is the role of the enzyme pepsin in the digestive system?
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Pepsin is a digestive enzyme that specifically breaks down proteins into smaller peptides. Options a, c, and d describe functions associated with other digestive enzymes or processes.

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47 In which organ does the majority of nutrient absorption occur in the human digestive system?
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The small intestine is the primary site for nutrient absorption due to its extensive surface area with villi and microvilli. This efficient absorption process ensures essential nutrients are assimilated into the bloodstream for various metabolic functions. Options a, c, and d are associated with other digestive or metabolic functions. The stomach initiates protein digestion, the large intestine focuses on water absorption, and the liver contributes to metabolic processes but is not a site for nutrient absorption.
48 Which phylum do insects belong to in the animal kingdom classification?
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Insects belong to the phylum Arthropoda, which is characterized by segmented bodies and exoskeletons made of chitin. This diverse phylum includes not only insects but also arachnids, crustaceans, and myriapods. Options a, c, and d correspond to other animal phyla--Mollusca, Chordata, and Annelida, respectively--each with distinct characteristics such as soft bodies, notochords, or segmented worms, setting them apart from insects in the animal kingdom.

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49 Which organ system is responsible for producing hormones that regulate various body functions?
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The endocrine system is tasked with producing hormones that act as chemical messengers, regulating a multitude of physiological processes in the body. These hormones are released directly into the bloodstream and target specific organs or tissues. Options a, b, and d are associated with other organ systems: the digestive system focuses on nutrient processing, the nervous system on electrical signaling, and the respiratory system on gas exchange.
50 Which of the following is an example of a monosaccharide?
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Glucose is a monosaccharide, representing the simplest form of sugar, consisting of a single sugar unit. Options b, c, and d, on the other hand, are examples of disaccharides--sucrose, lactose, and maltose--each composed of two sugar molecules through chemical bonding.

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51 Which organelle is responsible for breaking down and recycling cellular waste and debris?
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Lysosomes contain digestive enzymes and are responsible for breaking down cellular waste, damaged organelles, and foreign materials. While other organelles contribute to cellular functions, none specialize in the recycling process like lysosomes.
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Quality starts with who wrote the material. Our writers:

Gioia Degenaars, MS, has been a science instructor and department chairperson for over 15 years. She obtained her degree in biology from Kings College and her teaching certification through the College of Saint Elizabeth.

Susan Phillips, has been teaching high school science and biology, including advance placement biology, for over 25 years in South Carolina. She currently works as a curriculum developer for instruction in biology. Susan has won numerous teaching awards over the years, including Teacher of the Year. She received her Bachelor of Science degree from Baptist University.

Ann Auman, is a professor of biology at Pacific Lutheran University in Washington state. She has taught undergraduate biology for over 15 years. Ann received her Bachelor of Science degree from Pennsylvania State University and her doctorate from the University of Washington.

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