Nokea
Which of the following cell organelles is the site of lipid synthesis?
- A. smooth endoplasmic reticulum
- B. ribosome
- C. rough endoplasmic reticulum
- D. Golgi apparatus
Correct Answer: A
Rationale: The correct answer is the smooth endoplasmic reticulum. This organelle lacks ribosomes on its surface, unlike the rough endoplasmic reticulum, which is involved in protein synthesis. The enzymes present in the smooth endoplasmic reticulum are responsible for synthesizing lipids such as phospholipids and steroids. Choice B, ribosomes, are responsible for protein synthesis and not lipid synthesis. Choice C, rough endoplasmic reticulum, is involved in protein synthesis due to the presence of ribosomes. Choice D, Golgi apparatus, is responsible for modifying, sorting, and packaging proteins for secretion, not lipid synthesis.
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Which of the following is NOT a function of progesterone in the female reproductive system?
- A. expression of secondary sexual characteristics, such as enlarged breasts
- B. stimulation of milk production in the breasts
- C. regulation and preparation of the endometrial lining of the uterus for potential pregnancy
- D. inhibition of contractions of the uterus as the ovum is released
Correct Answer: A
Rationale: Progesterone plays a key role in the regulation and preparation of the endometrial lining of the uterus for potential pregnancy. It also inhibits contractions of the uterus as the ovum is released and stimulates milk production in the breasts. However, the expression of secondary sexual characteristics, such as enlarged breasts, is primarily influenced by estrogen, not progesterone. Therefore, choice A is the correct answer as it is not a function directly attributed to progesterone in the female reproductive system.
Where is the pineal gland located in the body?
- A. Below the larynx
- B. Above the kidney
- C. At the center of the brain hemispheres
- D. At the base of the brain
Correct Answer: C
Rationale: The pineal gland is correctly located at the center of the brain, between the two hemispheres. It is a small endocrine gland often referred to as the 'third eye' due to its unique location. Choices A, B, and D are incorrect as the pineal gland is not situated below the larynx, above the kidney, or at the base of the brain.
Neurotransmitters send chemical messages across the gap between one neuron and another through which of the following structures?
- A. Schwann cell
- B. ganglion
- C. synapse
- D. axon
Correct Answer: C
Rationale: Neurotransmitters send chemical messages across the gap between one neuron and another through a structure called the synapse. The synapse is a specialized junction where the axon of one neuron meets the dendrite or cell body of another neuron. Neurotransmitters are released from the axon terminal of the presynaptic neuron and travel across the synaptic cleft to bind to receptors on the postsynaptic neuron, transmitting the signal between the two neurons.
Choice A, Schwann cell, is incorrect as Schwann cells are responsible for producing myelin sheath around axons in the peripheral nervous system, not for transmitting neurotransmitters between neurons.
Choice B, ganglion, is incorrect as ganglia are clusters of nerve cell bodies outside the central nervous system and do not directly participate in the transmission of chemical messages between neurons.
Choice D, axon, is incorrect as the axon is a long, slender projection of a neuron that conducts electrical impulses away from the cell body and towards the axon terminals, where neurotransmitters are released into the synapse, but it is not the structure across which neurotransmitters travel to communicate between neurons.
Which of the following describes how atomic radius varies across the periodic table?
- A. Atomic radius increases from top to bottom and left to right on the periodic table.
- B. Atomic radius increases from top to bottom and right to left on the periodic table.
- C. Atomic radius increases from top to bottom and toward the halogens on the periodic table.
- D. Atomic radius increases from top to bottom and toward the noble gases on the periodic table.
Correct Answer: A
Rationale: Atomic radius tends to increase from top to bottom and left to right on the periodic table. This is because as you move down a group (top to bottom), new energy levels are added, increasing the distance of the outer electrons from the nucleus and thus increasing the size of the atom. On the other hand, as you move from left to right across a period, the number of protons and electrons increases, leading to a stronger nuclear charge that attracts the electrons closer to the nucleus, resulting in smaller atomic radii. Choice B is incorrect as atomic radius does not increase from right to left. Choices C and D are incorrect as they incorrectly associate the trend with specific groups of elements (halogens and noble gases) rather than the general trend observed on the periodic table.
Where does fertilization typically occur in the female reproductive system?
- A. uterus
- B. fallopian tube
- C. endometrium
- D. ovary
Correct Answer: B
Rationale: Fertilization typically occurs in the fallopian tube, specifically in the ampulla, which is the widest part of the tube. After ovulation, the released egg travels through the fallopian tube where it may encounter sperm for fertilization to take place. The fallopian tube provides the ideal environment for fertilization due to the presence of cilia that help move the egg and sperm towards each other. The uterus is where the fertilized egg will implant and develop into a fetus, not where fertilization occurs. The endometrium is the lining of the uterus that thickens to support a potential pregnancy but is not the site of fertilization. The ovary releases the egg during ovulation but is not where fertilization occurs.