Biology Questions

Q:

The NADPH required for the calvin cycle comes from

A) Reactions initiated in photosystem 1 B) Citric acid cycle
C) Reactions initiated in photosystem 2 D) Glycolysis
 
Answer & Explanation Answer: C) Reactions initiated in photosystem 2

Explanation:

ATP and NADPH produced by the light reactions are used in the Calvin cycle to reduce carbon dioxide to sugar. The Calvin cycle is similar to the Krebs cycle in that the starting material is regenerated by the end of the cycle.

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Q:

Reuptake refers to the

A) reabsorption of excess neurotransmitter molecules by a sending neuron B) release of hormones into the bloodstream
C) movement of neurotransmitter molecules across a synaptic gap D) inflow of myelin through an axon membrane
 
Answer & Explanation Answer: A) reabsorption of excess neurotransmitter molecules by a sending neuron

Explanation:

Reuptake refers to the process in the brain of neurons to retrieve chemicals that were not received by the next neuron. Neurons are cells in the brain that have miniscule spaces between them. They communicate with each other by sending chemicals across the space to the next neuron.

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Q:

Who discovered the monomers of nucleic acids?

A) James Watson, Francis Crick, and Rosalind Franklin B) Friedrich Miescher
C) Phoebus Levene D) Gerardus Johannes Mulder and Jöns Jacob Berxelius
 
Answer & Explanation Answer: C) Phoebus Levene

Explanation:

Deoxyribonucleic acid (DNA) is a nucleic acid polymer composed of monomers called nucleotides. Nucleotides are composed of three components: (1) a pentose sugar; (2) a nitrogenous base; and (3) one to three phosphate groups.

Phoebus Levene, a Russian biochemist was the first to discover the nucleotide and the first to correctly identify the way nucleic acid molecules, DNA.

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Q:

Which of the following is true of kinetochores?

A) They are the primary centrosome structures that maintain the attachment of the sister chromatids prior to mitosis. B) They are the sites at which microtubules attach to chromosomes.
C) They are located at the center of the centrosome and organize tubulin into spindle fibers. D) They cross at the cell's equator and move against each other, causing the cell to elongate.
 
Answer & Explanation Answer: B) They are the sites at which microtubules attach to chromosomes.

Explanation:

They are the sites at which microtubules attach to chromosomes.

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Q:

All of the following are true of neurons except that

A) they conduct a nervous impulse B) they are a very specialized form of connective tissue
C) thay are separated from one another by synapses D) When mature, they lose ability to divide
 
Answer & Explanation Answer: B) they are a very specialized form of connective tissue

Explanation:

All of the following are true of neurons except that they are a very specialized form of connective tissue.

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Q:

Plants are green because they

A) Refract green light B) Absorbs green light
C) Reflects green light D) Do not absorb ultra violet light
 
Answer & Explanation Answer: C) Reflects green light

Explanation:
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Q:

Rickets is caused due to the deficiency of

A) Carotene B) Cyanocobalamine
C) Thiamine D) Calciferol
 
Answer & Explanation Answer: D) Calciferol

Explanation:
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Q:

Which of the following statements about aldosterone is NOT correct?

A) Aldosterone increases sodium reabsorption by increasing the number of Na+-K+ ATPase pumps in the luminal membrane of the proximal tubule. B) Aldosterone is stimulated by decreased plasma sodium levels and increased plasma potassium levels.
C) Aldosterone is produced in the adrenal cortex. D) Aldosterone increases the number of passive sodium channels in the luminal membrane of the distal tubule and collecting duct, thus aiding sodium reabsorption.
 
Answer & Explanation Answer: A) Aldosterone increases sodium reabsorption by increasing the number of Na+-K+ ATPase pumps in the luminal membrane of the proximal tubule.

Explanation:

Aldosterone, the main mineralocorticoid hormone, is a steroid hormone produced by the zona glomerulosa of the adrenal cortex in the adrenal gland. It is essential for sodium conservation in the kidney, salivary glands, sweat glands and colon.

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