Which of the following is the main function of centrosomes in animal cells?
A. . Organelle trafficking.
B. Pathogen digestion.
C. Cytoplasm formation
D. Microtubule organization
Microtubule organization.
Centrosomes are organelles that serve as the main microtubule-organizing centers for animal cells.
They regulate the movement of microtubules and other cytoskeletal structures, thereby facilitating changes in the shapes of the membranes of animal cells.
Choice A, Organelle trafficking, is not the correct answer because while centrosomes do play a role in intracellular trafficking during interphase by organizing an astral ray of microtubules, their main function is microtubule organization.
Choice B, Pathogen digestion, is not the correct answer because centrosomes do not play a direct role in pathogen digestion.
Choice C, Cytoplasm formation, is not the correct answer because centrosomes do not play a direct role in cytoplasm formation.
Therefore, the Correct Answer is D.
More Questions on TEAS 7 Science
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Q #1: Which of the following results in osteoporosis?
A. An increase in osteocyte activity while osteoclast activity continues at expected levels.
B. A decline in osteoclast activity while osteoblast activity continues at expected levels.
C. An increase in osteocyte activity while osteoblast activity reduces.
D. A decline in osteoblast activity while osteoclast activity continues at expected levels.
Answer Explanation
A decline in osteoblast activity while osteoclast activity continues at expected levels results in osteoporosis.
Osteoporosis is caused by an imbalance between the functioning of osteoclast and osteoblast cells.
Osteoblasts are responsible for forming new bone, while osteoclasts break down old bone.
If osteoblast activity declines while osteoclast activity continues at expected levels, this means that more bone is being broken down than is being formed, leading to a loss of bone density and an increased risk of osteoporosis.
Choice A is incorrect because an increase in osteocyte activity would not result in osteoporosis.
Osteocytes are mature bone cells that maintain the mineral concentration of the bone matrix.
Choice B is incorrect because a decline in osteoclast activity would not result in osteoporosis.
Osteoclasts break down old bone, so a decline in their activity would mean that less bone is being broken down.
Choice C is incorrect because an increase in osteocyte activity would not result in osteoporosis.
As mentioned earlier, osteocytes are mature bone cells that maintain the mineral concentration of the bone matrix.
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Q #2: The pleura is a connective tissue sheath that covers which of the following organs?
A. Liver
B. Heart.
C. Spleen
D. Lung
Answer Explanation
The pleura is a double-layered serous membrane that covers each lung and lines the thoracic cage
The pleura is a vital part of the respiratory tract.
Its role is to cushion the lung and reduce any friction that may develop between the lung, rib cage, and chest cavity.
Each pleura (there are two) consists of a two-layered membrane that covers each lung.
The layers are separated by a small amount of viscous (thick) lubricant known as pleural fluid.
The pleura is comprised of two distinct layers: the visceral pleura and the parietal pleura.
The visceral pleura is the thin, slippery membrane that covers the surface of the lungs and dips into the areas separating the different lobes of the lungs (called the hilum).
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Q #3: Which of the following is a group that can be measured against the experimental group?
A. Responding
B. Manipulated
C. Control
D. Variable
Answer Explanation
Control.
A control group is a group in an experiment that does not receive the treatment or manipulation being tested and is used as a benchmark to measure how the other tested subjects do.
The control group is used to minimize the effects of all variables except the independent variable.
This allows researchers to determine if changes in the dependent variable are due to the manipulation of the independent variable or if they are due to some other factor.
Choice A.
Responding is not the correct answer because it refers to the dependent variable, which is the variable that is being measured in an experiment.
Choice B.
Manipulated is not the correct answer because it refers to the independent variable, which is the variable that is being manipulated in an experiment.
Choice D.
Variable is not the correct answer because it refers to any factor that can change in an experiment and can include both independent and dependent variables.
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Q #4: Which of the following structures in the female reproductive system secretes hormones to maintain the uterine lining during pregnancy?
A. Umbilical cord
B. Corpus luteum
C. Oviduct
D. Oocyte
Answer Explanation
The corpus luteum is a structure that develops in the ovary after an egg has been released.
It secretes the hormone progesterone, which prepares the uterus for a fertilized egg to implant and helps maintain the uterine lining during pregnancy1.
Choice A.
Umbilical cord is not correct because it is a structure that connects the developing fetus to the placenta and provides nutrients and oxygen to the fetus, but does not secrete hormones.
Choice C.
Oviduct is not correct because it is a tube that transports eggs from the ovary to the uterus, but does not secrete hormones.
Choice D.
Oocyte is not correct because it is an immature egg cell, but does not secrete hormones.
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Q #5: Which of the following ions binds to the troponin complex, initiating contraction of a muscle?
A. Potassium.
B. Calcium.
C. Phosphorus.
D. Sodium
Answer Explanation
Calcium ions play a crucial role in initiating muscle contraction.
When a muscle cell is stimulated to contract by an action potential, calcium channels open in the sarcoplasmic membrane and release calcium into the sarcoplasm.
Some of this calcium attaches to troponin, which causes it to change shape.
This shape change exposes binding sites for myosin on the actin filaments.
Myosin’s binding to actin causes crossbridge formation, and contraction of the muscle begins.
The other ions mentioned in the question do not have this specific role in muscle contraction.
Potassium ions are important for maintaining the resting membrane potential of cells, but they do not bind to the troponin complex.
Phosphorus ions are important for energy metabolism, but they do not bind to the troponin complex.
Sodium ions are important for generating action potentials, but they do not bind to the troponin complex.
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Q #6: Which of the following is correct regarding the pH scale?
A. A substance with a pH of 3 is two times more alkaline than a substance with a pH of 4
B. A substance with a pH of 3 is two times more acidic than a substance with a pH of 4
C. A substance with a pH of 3 is 10 times more acidic than a substance with a pH of 4
D. A substance with a pH of 3 is 10 times more alkaline than a substance with a pH of 4
Answer Explanation
The pH scale is a logarithmic scale that measures the acidity or alkalinity of a solution.
A solution with a pH of 7 is neutral, while a solution with a pH less than 7 is acidic and a solution with a pH greater than 7 is alkaline.
Because the pH scale is logarithmic, each whole number change in pH represents a tenfold change in acidity or alkalinity.
Therefore, a substance with a pH of 3 is 10 times more acidic than a substance with a pH of 4.
Choice A.
A substance with a pH of 3 is two times more alkaline than a substance with a pH of 4 is not correct because it incorrectly states that the substance with a lower pH is more alkaline and also incorrectly states the magnitude of the difference in acidity or alkalinity.
Choice B.
A substance with a pH of 3 is two times more acidic than a substance with a pH of 4 is not correct because it correctly states that the substance with a lower pH is more acidic but incorrectly states the magnitude of the difference in acidity.
Choice D.
A substance with a pH of 3 is 10 times more alkaline than a substance with a pH of 4 is not correct because it incorrectly states that the substance with a lower pH is more alkaline.
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Q #7: Stimulus: 1of 1. A group of students performed an experiment to test terminal velocity, which is the greatest speed obtained by a falling object. The students dropped different numbers of coffee filters and measured the resulting terminal velocity. Which of the following conclusions is supported by the data in the following data table? #OF FILTERS MASS (g) TERMINAL VELOCITY (m/s) 1 1.01 1.74 2 1.99 2.48 3 3.02 3.04 4 4.0 3.50 5 5.01 3.80
A. Terminal velocity is when the force of gravity is equal to air resistance.
B. Heavier objects take more time to reach terminal velocity.
C. Heavier objects fall faster than lighter objects.
D. The greater the number of filters, the smaller the terminal velocity.
Answer Explanation
Heavier objects fall faster than lighter objects.
The data in the table shows that as the number of filters (and therefore the mass) increases, the terminal velocity also increases.
This means that the heavier objects (with more filters) are falling faster than the lighter objects (with fewer filters).
Choice A is not supported by the data in the table as much as it is true.
Terminal velocity is indeed when the force of gravity is equal to air resistance, but this definition does not provide any information about the relationship between mass and terminal velocity.
Choice B is also not supported by the data in the table.
The data does not provide any information about the time it takes for an object to reach terminal velocity.
Choice D is not supported by the data in the table.
The data shows that as the number of filters increases, the terminal velocity also increases.
This means that the greater the number of filters, the greater (not smaller) the terminal velocity.
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Q #8: Which of the following is the number of protons in a lithium atom?
A. 7
B. 3
C. 12
D. 4
Answer Explanation
The atomic number of an element represents the number of protons in the nucleus of an atom of that element.
Since lithium has an atomic number of 3, it has 3 protons in its nucleus.
Choice A is not correct because 7 is the mass number of lithium, not the number of protons.
Choice C is not correct because 12 is not the atomic number or mass number of lithium.
Choice D is not correct because 4 is not the atomic number or mass number of lithium.
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Q #9: Which of the following microorganisms lack their own metabolic pathways and can only reproduce inside of a host cell?
A. Bacteria
B. Protozoa
C. Helminths
D. Viruses
Answer Explanation
Viruses.
Viruses lack essential machinery needed to reproduce by themselves.
In fact, viruses can only reproduce after infecting a living cell - a process called viral replication.
Once inside a living cell, viruses re-program the cell’s machinery to produce viral proteins and genetic material to make new copies of themselves.
Choice A, Bacteria, is not the correct answer because bacteria have their own metabolic pathways and can reproduce outside of a host cell.
Choice B, Protozoa, is also not the correct answer because protozoa are singlecelled eukaryotes that have their own metabolic pathways and can reproduce outside of a host cell.
Choice C, Helminths, is not the correct answer because helminths are multicellular parasitic worms that have their own metabolic pathways and can reproduce outside of a host cell.
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Q #10: In a hypertonic solution, water flows through aquaporins embedded in the plasma membrane of the cell. This type of transport is best known as which of the following?
A. Facilitated diffusion
B. Active transport
C. Osmosis
D. Diffusion
Answer Explanation
Osmosis is the movement of water molecules across a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration.
In a hypertonic solution, the concentration of solutes outside the cell is higher than inside the cell, so water flows out of the cell through aquaporins embedded in the plasma membrane to balance the concentration gradient.
Choice A.
Facilitated diffusion is not correct because it is a type of passive transport that involves the movement of molecules across a membrane through specific transport proteins, but it does not specifically refer to the movement of water molecules.
Choice B.
Active transport is not correct because it is a type of transport that involves the movement of molecules against their concentration gradient and requires energy in the form of ATP, but osmosis is a passive process that does not require energy.
Choice D.
Diffusion is not correct because it refers to the movement of molecules from an area of higher concentration to an area of lower concentration, but it does not specifically refer to the movement of water molecules.
