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