OAT Biology Practice Test

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All of these play an important role in human respiration EXCEPT

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Explanation:
The respiratory rate in humans will be affected by an increase in the amount of CO2 and a drop in pH levels, which is the same as an increase in hydrogen ion levels. Strenuous exercising will also modify the respiratory rate. O2 concentration generally does not play an important role in regulating respiration.

Animal cells vary from plant cells in that they have

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Explanation:
Animal cells have centrioles while plants do not require them. Both animal and plant cells have an endoplasmic reticulum, membrane-bound organelles, and lysosomes. Only plants have a cell wall made of cellulose and large vacuoles. Neither plants nor animals have circular DNA, this is a characteristic of the Kingdom Monera.

The liver is an important organ that performs all of the functions listed below. EXCEPT

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Explanation:
The liver does not break down peptides into amino acids. It performs all of the following functions: stores amino acids absorbed in the capillaries, as in as in (A); makes bile, as in (C); and store glycogen, (D); detoxifies harmful substances,

A symbiotic relationship is defined as which of the following?

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Explanation:
A symbiotic relationship is a relationship among two organisms in which both benefit. Choice (B) describes parasitism, . Choice (C) is an example of altruistic behaviour. Choice (A) described habituation.

Calypso bulbosa, the Calypso Orchid, grows in close proximity to mycorrhizal fungi. The fungus infiltrate the flower's roots and take use of the plant's food supply. Rare minerals, such as phosphates, are concentrated in the roots by the fungi and made readily available to the orchid. This is an example of

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Explanation:
This is an example of mutualism. Both organisms benefit. Choice (B), parasitism, is an example of a symbiotic relationship in which one organism benefits and the other is harmed. Choice Choice (C), endosymbiosis, is the idea that some organelles originated as symbiotic prokaryotes that live inside larger cells.(D), commensalism, is when one organism benefits and the other is unaffected.

Which of the following in cells may catalyze hydrogen peroxide processes, provide cellular energy, and create proteins in that order?

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Explanation:
Peroxisomes catalyze reactions that produce hydrogen peroxide, ribosomes are involved in protein synthesis, and mitochondria contain enzymes involved in cellular respiration. Eliminate (D), and (B) because lysosomes are the sites of degradation; they contain hydrolytic enzymes but do not produce hydrogen peroxide. Choice (A) is incorrect, as the Golgi apparatus sorts and packages substances that are destined to be secreted out of the cell. Interestingly, O2 concentration generally doesn't play an important role in regulating respiration.

Which of the following is NOT true about meiosis?

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Explanation:
Crossing-over and synapsis occur during meiosis, which produces haploid gametes. Separation of homologous chromosomes occurs during meiosis I, while separation of sister chromatids does not occur until meiosis II.

Which of the following characteristics of arteries is correct?

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Explanation:
Arteries are thick-walled vessels that carry blood away from the heart. Blood moves by contracting muscles. Choices (B) is a characteristics of veins. Veins are thin-walled vessels (with valves) that return blood to the heart. Choice (A) is an example of a vein. Choice (D) may or may not be true depending if the blood is being carried in the pulmonary circuit (lungs) or system circuit (rest of the body).

A change in the membrane potential of a neuron from +50 to -70 millivolts is considered

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Explanation:
A voltage change from +50 to -70 is called repolarization. Choice (B) is incorrect; a voltage change from -70 to -90 is called hyperpolarization. Choice (C) can be eliminated as well; an action potential is a travelling depolarized wave. It refers to the whole thing, from depolarization, repolarization, hyper-polarization, and back to resting potential. Eliminate choice (D) since this is what occurs at the end of a neuron and involves the release of neurotransmitters.

Which of the following factors has the greatest impact on a population's genetic variability?

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Explanation:
Mutations produce genetic variability. All of the other answer choices are forms of asexual reproduction. Gastrulation is a step in embryonic development in which three distinct germ layers are formed.

All enzymes in the synaptic cleft are shown to be denatured by a chemical agent. How will this agent affect acetylcholine?

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Explanation:
This question tests your ability to associate what happens when enzymes are denatured and what would happen in the synaptic cleft. Acetylcholinesterase is an enzyme that degrades acetylcholine in the synaptic cleft. If acetylcholinesterase is denatured, acetylcholine will still be released from the presynaptic membrane and continue to diffuse across the synaptic cleft and bind to the postsynaptic membrane because acetylcholine is not degraded.

In plant intercellular communication, which of the following is used?

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Explanation:
Plasmodesmata are cytoplasmic strands that interconnect cells and form an intercellular communication network within a plant body. Gap junctions are used in intercellular communication with animals, but are not found in plants, so eliminate (B). Desmosomes are used in maintaining connectivity of tissues and Hemidesmosomes are special desmosomes used in skin, so eliminate (A) and (D).

The energy that electrons give up as they go through the electron transport chain is used to

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Explanation:
Electrons passed down along the electron transport chain from one carrier to another lose energy and provide energy for making ATP, eliminate (C). Glucose is decomposed during glycolysis, but this process is not associated with energy given up by electrons; eliminate (D). Glucose is made during photosynthesis, so eliminate (A).

Which of the assertions regarding trypsin is untrue?

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Explanation:
Trypsin is an enzyme, which are proteins and organic catalysts that speed up reactions without altering them. One of its reactions involves the conversion of chymotrypsinogen to chymotrypsin, eliminate (B). They are not consumed in the process. Therefore, you can eliminate (A) and (C).

The sympathetic nervous system stimulates all of the following EXCEPT

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Explanation:
The sympathetic division is active during emergency situations. This leads to a decrease in peristalsis in your gastrointestinal tract. (Your stomach shuts down.) Stimulation of the sympathetic nervous system leads to (B), pupils dilating, (C), peripheral blood vessels constricting, (D), sweating.

The main site of glucose absorption is the

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Explanation:
The primary site of glucose reabsorption is the proximal convoluted tubule. The glomerulus, (C), is a tuft of capillaries that filters fluid into the Bowman's capsule. Choice (A) and (B), the loop of Henle, is the site of salt reabsorption. Choice (D), the collecting duct, is the site in which urine is concentrated.

Which of the following is NOT a feature of animal asexual reproduction?

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Explanation:
There is no union of gametes in mitosis. Choices (B) and (D) are incorrect: Asexual reproduction involves the production of two new cells with the same number of chromosomes as the parent cell. If the parent cell is diploid, then the daughter cells will be diploid. The daughter cells are identical to each other and to the parent cell, so eliminate (A).

At least one of these two main components is found in every virus. They are

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Explanation:
Viruses are made up of nucleic acid surrounded by a protein coat called a capsid. They do not contain a cell wall, proteins, or cell membrane.

During reproduction, which of the following occurs

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Explanation:
Ovulation is the first to occur of those mentioned in the question. Ovulation is the release of an egg from the ovary into the fallopian tube. It is followed by fertilization (D) in the fallopian tubes. The zygote will then undergo a series of steps before implantation into the endometrium (A), neurulation (B).

DNA's base composition differs between species. Which of the following ratios do you think will stay the same in DNA?

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Explanation:
The ratio of purines to pyrimidines should be constant because purines always bind with pyrimidines, no matter which ones they may be.

Which of the following features are shared by bacteria and fungi?

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Explanation:
They both contain genetic material (DNA), a plasma membrane, and a cell wall. Unlike fungi, bacteria lack a definite nucleus. Therefore, eliminate (D). Bacteria are unicellular, whereas fungi are both unicellular and multicellular. Therefore, eliminate (A), (C). All those options contain membrane-bound organelles (mitochondria and golgi)

Metafemale syndrome, a condition in which a woman has an extra X chromosome. This could be caused by a failure in

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Explanation:
The failure in oogenesis that could produce this syndrome would occur in anaphase I or anaphase II. Anaphase refers to the stage of meiosis in which chromatids separate from each other. If the chromosomes or chromatids fail to separate during anaphase, one egg cell will contain two X chromosomes instead of one.

In DNA replication, which of the following does NOT happen?

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Explanation:
DNA polymerase, not RNA polymerase, is the enzyme that causes the DNA strands to elongate. DNA helicase unwinds the double helix, so (A) is true and therefore incorrect. Choice (B), DNA ligase seals the discontinuous Okazaki fragments, is also true. Eliminate it. In the presence of DNA polymerase, DNA strands always grow in the 5' to 3' direction as complementary bases attach. Therefore, (D) is also incorrect. Topoisomerase is used to prevent over-winding and underwinding, (E) is incorrect.

Which of the following statements about organisms that are the first to establish an ecologically successional habitat is correct?

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Explanation:
Pioneer organisms colonize an area that is not habitable by other organisms and alter it over time in a way that makes the area habitable for other organisms. Pioneer organisms are producers, such as lichens that are symbionts—an intertwined relationship of a fungus and an algae.

A frameshift mutation is which of the following?

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Explanation:
A frameshift mutation is one in which the reading frame for the protein construction machinery is shifted. It is a deletion or addition of nucleotides in a number that is not a multiple of 3. Often this can lead to premature stop codons, which lead to nonfunctional proteins.

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