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

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Answer Explanation:

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 Exam 2

Question 1:

To separate genomic DNA fragments by size, which of these laboratory methods is most useful?

A. Titration

B. Electrophoresis

C. Filtration

D. Spectrophotometry

The Correct Answer is B.

Electrophoresis is the most useful laboratory method for separating genomic DNA fragments by size.

Electrophoresis is a technique that uses an electric field to separate charged molecules, such as DNA fragments, based on their size and charge.

 

Choice A is not correct because titration is a laboratory method used to determine the concentration of a solution.

Choice C is not correct because filtration is a laboratory method used to separate solids from liquids.

Choice D is not correct because spectrophotometry is a laboratory method used to measure the absorbance of light by a solution.


Question 2:

Which of the following can lead to a tsunami?

 

A. Sunspot activity

B. Lightning strikes.

C. Earthquakes

D. Flooding.

The Correct Answer is C.

A tsunami is a catastrophic ocean wave that is usually caused by a submarine earthquake.

It can also be caused by an underwater or coastal landslide, the eruption of a volcano, or the impact of a meteor or comet in a body of water.

 

Choice A is not correct because sunspot activity does not cause tsunamis.

Choice B is not correct because lightning strikes do not cause tsunamis.

Choice D is not correct because flooding does not cause tsunamis.


Question 3:

Which of the following allows the AIDS virus, which contains RNA, to insert viral DNA into the DNA of a host cell after the AIDS virus enters the cell?

A. The phospholipids found on the envelope of the virus.

B. Reverse transcriptase, an enzyme encoded by the virus.

C. Receptor proteins located on the surface of the virus.

D. The protein that makes up the capsid of the virus.

The Correct Answer is B.

Reverse transcriptase, an enzyme encoded by the virus.

Reverse transcriptase is a virus-specific enzyme that transcribes an RNA template to DNA1.

This allows the AIDS virus, which contains RNA, to insert viral DNA into the DNA of a host cell after the AIDS virus enters the cell.

 

Choice A, The phospholipids found on the envelope of the virus, is not the correct answer because phospholipids are a major component of cell membranes and do not play a direct role in inserting viral DNA into the DNA of a host cell.

Choice C, Receptor proteins located on the surface of the virus, is not the correct answer because receptor proteins located on the surface of the virus play a role in attachment and fusion of HIV virons to host cells, but do not play a direct role in inserting viral DNA into the DNA of a host cell.

Choice D, The protein that makes up the capsid of the virus, is not the correct answer because capsid is the outer protein shell of a virus and does not play a direct role in inserting viral DNA into the DNA of a host cell.


Question 4:

In a plant in which fuzzy leaves (F) are dominant over smooth leaves (f), which of the following crosses will produce only offspring with smooth leaves? 

 

A. FF x FF

B. Ff x Ff

C. ff x ff

D. Ff x ff

The Correct Answer is C.

ff.

In this cross, both parents are homozygous recessive for the smooth leaf trait

(ff).

This means that all of their offspring will inherit two copies of the recessive allele (f) and will therefore have smooth leaves.

Choice A.

FF x FF is not correct because both parents are homozygous dominant for the fuzzy leaf trait (FF) and all of their offspring will inherit two copies of the dominant allele (F) and will therefore have fuzzy leaves.

Choice B.

Ff x Ff is not correct because both parents are heterozygous for the leaf trait (Ff) and their offspring can inherit either one dominant allele (F) or one recessive allele (f) from each parent, resulting in a 3:1 ratio of fuzzy to smooth leaves. Choice D.

Ff x ff is not correct because one parent is heterozygous for the leaf trait (Ff) while the other is homozygous recessive (ff), resulting in a 1:1 ratio of fuzzy to smooth leaves in their offspring.

 


Question 5:

Which of the following glands synthesizes antidiuretic hormone?

A. Pineal gland

B. Thymus

C. Hypothalamus

D. Pancreas

The Correct Answer is C.

The hypothalamus is a region of the brain that synthesizes antidiuretic hormone (ADH), also known as vasopressin.

ADH is then transported to the posterior pituitary gland via neurohypophysial capillaries, where it is stored until it is ready to be secreted into the circulation.

 

Choice A.

Pineal gland is not correct because it is a small endocrine gland located in the brain that secretes the hormone melatonin, which regulates sleep-wake cycles, but it does not synthesize ADH.

Choice B.

Thymus is not correct because it is a gland located in the chest that produces hormones involved in immune system development, but it does not synthesize ADH.

Choice D.

Pancreas is not correct because it is a gland located behind the stomach that secretes hormones such as insulin and glucagon, which regulate blood sugar levels, but it does not synthesize ADH.


Question 6:

Which of the following organic molecules contain both an amine and carboxyl group?

A. Lipids

B. Chitin

C. Cellulose

D. Proteins

The Correct Answer is D.

Proteins.

Proteins are made up of amino acids which are organic molecules that contain both an amine functional group (–NH2) and a carboxylic acid functional group (– COOH).

 
 

Choice A, Lipids, is not the correct answer because lipids are a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins, monoglycerides, diglycerides, triglycerides, phospholipids, and others.

They do not contain both an amine and carboxyl group.

Choice B, Chitin, is not the correct answer because chitin is a long-chain polymer of N-acetylglucosamine, a derivative of glucose.

It does not contain both an amine and carboxyl group.

Choice C, Cellulose, is not the correct answer because cellulose is an organic compound with the formula (C6H10O5)n, a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units.

It does not contain both an amine and carboxyl group.


Question 7:

Which of the following processes causes most of the carbon dioxide from the blood to move into the alveoli?

 

A. Conversion to carbon monoxide.

B. Diffusion down a concentration gradient.

C. Passive transport using carrier proteins.

D. Active transport using energy.

The Correct Answer is B.

Diffusion down a concentration gradient causes most of the carbon dioxide from the blood to move into the alveoli.

The alveoli are tiny air sacs in the lungs where gas exchange occurs.

Carbon dioxide is a waste product of cellular respiration and is carried by the blood to the lungs to be exhaled.

In the lungs, carbon dioxide diffuses from the blood (where its concentration is high) into the alveoli (where its concentration is lower) down its concentration gradient.

 

Choice A is incorrect because carbon dioxide is not converted to carbon monoxide in the body.

Choice C is incorrect because passive transport using carrier proteins is not the primary mechanism by which carbon dioxide moves from the blood into the alveoli.

Choice D is incorrect because active transport using energy is not involved in the movement of carbon dioxide from the blood into the alveoli.

 


Question 8:

Which of the following indicates the function of sodium bicarbonate secreted by the pancreas?

A. Sodium bicarbonate is a protease that digests carbohydrates.

B. Sodium bicarbonate stimulates the pyloric sphincter.

C. Sodium bicarbonate inhibits peristalsis.

D. Sodium bicarbonate neutralizes the acidity of chyme.

The Correct Answer is D.

Sodium bicarbonate neutralizes the acidity of chyme.

The pancreas secretes large amounts of sodium bicarbonate, which protects the duodenum by neutralizing the acid that comes from the stomach.

This compound helps neutralize stomach acid generated during the digestive process.

 

Choice A is incorrect because sodium bicarbonate is not a protease that digests carbohydrates.

Proteases are enzymes that break down proteins, while sodium bicarbonate is a chemical compound that helps neutralize stomach acid.

Choice B is incorrect because sodium bicarbonate does not stimulate the pyloric sphincter.

The pyloric sphincter is a ring of smooth muscle that separates the stomach from the duodenum and regulates the passage of partially digested food (chyme) into the small intestine.

Choice C is incorrect because sodium bicarbonate does not inhibit peristalsis.

Peristalsis is a series of wave-like muscle contractions that move food through the digestive tract.

 


Question 9:

Which of the following types of cells produce and release antibodies?

A. Natural killer cells

B. Cytotoxic T-cells

C. Plasma B cells

D. Helper T-cells

The Correct Answer is C.

Plasma B cells.

Antibodies are produced by specialized white blood cells called B lymphocytes (or B cells).

When an antigen binds to the B-cell surface, it stimulates the B cell to divide and mature into a group of identical cells called a clone.

The mature B cells, called plasma cells, secrete millions of antibodies into the bloodstream and lymphatic system.

 

Choice A, Natural killer cells, is not the correct answer because natural killer cells are a type of white blood cell that play a major role in the host-rejection of both tumors and virally infected cells.

Choice B, Cytotoxic T-cells, is not the correct answer because cytotoxic T-cells are a type of white blood cell that kills cancer cells, cells that are infected (particularly with viruses), or cells that are damaged in other ways.

Choice D, Helper T-cells, is not the correct answer because helper T-cells are a type of white blood cell that play an important role in the immune system by helping other white blood cells fight infections.


Question 10:

Parasitic worm infestation is hypothesized to be damaging to the host.

However, scientists have recently discovered that worm infestation can relieve the effects of certain autoimmune disorders.

In which of the following ways should the hypothesis be modified, given the new findings?

 

A. Worm infestation prevents the body from immune malfunction

B. Worm infestation reduces the severity of certain autoimmune disorders

C. Worm infestations exacerbate the body's immune reactions

D. Lack of worm infestations is the cause of some autoimmune disorders

The Correct Answer is B.

The hypothesis should be modified to include the new findings that worm infestation can relieve the effects of certain autoimmune disorders.

A possible modification could be: “Parasitic worm infestation can have both damaging and beneficial effects on the host.

While it can cause harm, it has also been found to reduce the severity of certain autoimmune disorders.”

Choice A.

Worm infestation prevents the body from immune malfunction is not correct because it overstates the findings and implies that worm infestation completely prevents immune malfunction, which is not supported by the evidence.

Choice C.

Worm infestations exacerbate the body’s immune reactions is not correct because it contradicts the new findings that worm infestation can relieve the effects of certain autoimmune disorders.

Choice D.

Lack of worm infestations is the cause of some autoimmune disorders is not correct because it overstates the findings and implies a causal relationship between lack of worm infestations and autoimmune disorders, which is not supported by the evidence.