Nokea
With respect to a male erection which of the following statements is incorrect.
- A. During an erection there is an increase in the activity of parasympathetic nervous system
- B. A male erection is triggered by motor inputs to the higher brain regions
- C. During an erection there is a decrease in the activity of the sympathetic nervous system
- D. A male erection results from dilatation of arterioles in the penis
Correct Answer: B
Rationale: The correct answer is B because it is incorrect to say that a male erection is triggered by motor inputs to the higher brain regions. Erections are primarily controlled by the autonomic nervous system, specifically the parasympathetic division. Parasympathetic activity leads to vasodilation of penile blood vessels, resulting in increased blood flow and erection. Choices A, C, and D are incorrect because during an erection, there is indeed an increase in parasympathetic activity, a decrease in sympathetic activity, and dilation of arterioles in the penis.
You may also like to solve these questions
_____________________ is a vascular organ that is formed within the uterine wall
- A. Amnion
- B. Chorion
- C. Placenta
- D. Endometrium
Correct Answer: C
Rationale: The correct answer is C: Placenta. The placenta is a vascular organ that develops within the uterine wall during pregnancy. It serves as a connection between the mother and fetus for nutrient and waste exchange. The amnion (A) and chorion (B) are fetal membranes, not vascular organs, and the endometrium (D) is the inner lining of the uterus where the placenta attaches.
Umbilical cord contains _________
- A. Pluripotent stem cells
- B. Cord blood stem cells
- C. Blood stem cells
- D. None of the above
Correct Answer: B
Rationale: The correct answer is B: Cord blood stem cells. Umbilical cord blood contains stem cells that are collected from the blood in the umbilical cord and placenta after a baby is born. These stem cells are known as cord blood stem cells, which are multipotent and have the potential to develop into various types of cells in the body. Pluripotent stem cells (choice A) refer to stem cells that can differentiate into almost any cell type, which is not specifically present in the umbilical cord. Blood stem cells (choice C) are found in bone marrow and are responsible for producing blood cells, but they are not the primary type of stem cells found in umbilical cord blood. Choice D is incorrect because umbilical cord blood indeed contains cord blood stem cells.
Reproduction in humans usually requires
- A. the process of cloning
- B. mitotic cell division of gametes
- C. gametes with chromosomes that are not paired
- D. the external fertilization of sex cells
Correct Answer: C
Rationale: The correct answer is C because reproduction in humans typically involves the fusion of gametes with chromosomes that are not paired, resulting in the formation of a zygote with a complete set of paired chromosomes. This process is known as sexual reproduction. Choice A, cloning, does not involve the fusion of gametes and is a form of asexual reproduction. Choice B, mitotic cell division of gametes, is incorrect as gametes undergo meiosis to form haploid cells, not mitosis. Choice D, external fertilization of sex cells, is not typical in humans as fertilization usually occurs internally.
Which of the following events does NOT lead to genetic variation?
- A. Independent assortment of chromosomes during meiosis.
- B. Random fertilization between ovum and sperm.
- C. Crossing over between homologous chromosomes during meiosis I.
- D. Crossing over between homologous chromosomes during meiosis II.
Correct Answer: D
Rationale: The correct answer is D. Crossing over between homologous chromosomes during meiosis II does not lead to genetic variation. This is because crossing over occurs during meiosis I, not meiosis II. Meiosis II is when the separated chromatids are pulled apart to form haploid cells. Independent assortment of chromosomes during meiosis (A) and random fertilization between ovum and sperm (B) both contribute to genetic variation by creating unique combinations of alleles. Crossing over between homologous chromosomes during meiosis I (C) also leads to genetic variation by exchanging genetic material between homologous chromosomes.
Bat shaped bone that form part of the base of the skull is called as
- A. Ethmoid bone
- B. Sphenoid bone
- C. Parietal bone
- D. Occipital bone
Correct Answer: B
Rationale: The correct answer is B: Sphenoid bone. The sphenoid bone is bat-shaped and forms part of the base of the skull. It is located in the middle of the skull, helping to connect the cranial bones. The other choices, A: Ethmoid bone, C: Parietal bone, and D: Occipital bone, do not match the description of a bat-shaped bone at the base of the skull. The ethmoid bone is located between the eyes, the parietal bone forms the top and sides of the skull, and the occipital bone forms the back and base of the skull. Therefore, B is the correct answer based on the specific description given in the question.