Nokea
Which of the following is an example of ovoviviparity?
- A. Honeybees lay soft eggs within the hive
- B. Sharks hatch from shell-covered fertilized eggs within the female's body.
- C. Birds hatch from shell covered fertilized eggs laid within a nest.
- D. Fetal mammals obtain nourishment from the mother through a placent
Correct Answer: C
Rationale: Ovoviviparity is a reproductive strategy where fertilized eggs develop within the female's body but are not nourished by the mother. Choice C is correct because birds lay fertilized eggs within a nest where they hatch, indicating the eggs were developed internally. Choice A is incorrect as honeybees do not exhibit ovoviviparity. Choice B is incorrect as sharks exhibit viviparity, where embryos develop inside the mother but are nourished directly. Choice D is incorrect as it describes placental nourishment in mammals, which is not characteristic of ovoviviparity.
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Medial lower arm bone is
- A. Humerus
- B. Radius
- C. Ulna
- D. Carpals
Correct Answer: C
Rationale: The correct answer is C: Ulna. The ulna is the medial lower arm bone located on the pinky side. It articulates with the humerus at the elbow joint and with the radius at the wrist joint. The humerus (A) is the upper arm bone, not located in the lower arm. The radius (B) is the lateral lower arm bone, not the medial one. Carpals (D) refer to the wrist bones, not the lower arm bones. Therefore, the ulna is the correct answer as it is the specific bone that fits the description of being the medial lower arm bone.
At the level of the testicle, the straight tubules:
- A. are located inside the lobules;
- B. continue the convoluted seminiferous tubules;
- C. open in the rete testis;
- D. open in the epididymal duct;
Correct Answer: C
Rationale: The correct answer is C because the straight tubules open into the rete testis, which is a network of tubules located at the hilum of the testis. This is where sperm produced in the seminiferous tubules are collected and transported to the epididymis for maturation. The other choices are incorrect because A is not accurate as straight tubules are not located inside the lobules, B is incorrect as straight tubules are a separate structure from the convoluted seminiferous tubules, and D is inaccurate as straight tubules do not open directly into the epididymal duct.
Failure of the testes to descend into mitotic cell divisions occur as the the scrotum is a condition known as zygote travels down the uterine ________.
- A. phimosis
- B. the acrosomal reaction
- C. cryptorchidism
- D. cleavage
Correct Answer: C
Rationale: The correct answer is C: cryptorchidism. Cryptorchidism is the condition where one or both testes fail to descend into the scrotum. This leads to impaired spermatogenesis as the temperature in the abdominal cavity is too high for proper sperm production. Phimosis (A) is the narrowing of the opening of the foreskin, unrelated to testicular descent. The acrosomal reaction (B) is a process during fertilization, not related to testicular descent. Cleavage (D) refers to the rapid mitotic cell divisions of the zygote, not associated with testicular descent.
Which of the following components of the fetoplacental (endocrine) unit is similar to thyroid stimulating hormone (TSH) and stimulates T4 secretion by the maternal thyroid?
- A. Human chorionic gonadotropin (hCG)
- B. Human chorionic somatomammotropin (hCS, hPL)
- C. IGF I and IGF II
- D. Endothelial growth factor (EGF)
Correct Answer: A
Rationale: Rationale:
1. Human chorionic gonadotropin (hCG) acts like TSH, stimulating T4 secretion by the maternal thyroid.
2. hCG is produced by the placenta and has a similar structure and function to TSH.
3. hCG binds to the TSH receptor on the thyroid gland, triggering T4 release.
4. Other options do not specifically target the thyroid gland for T4 secretion.
Summary:
A: hCG mimics TSH and directly stimulates T4 release.
B: hCS, hPL - involved in placental growth and lactation, not thyroid stimulation.
C: IGF I and II - growth factors, not directly related to thyroid function.
D: EGF - promotes cell growth and differentiation, not linked to thyroid hormone secretion.
The ovule that can be fecundated contains:
- A. 22 somatic chromosomes;
- B. 23 autosomes;
- C. a sex chromosome: X or Y;
- D. 11 pairs of somatic chromosomes;
Correct Answer: B
Rationale: The correct answer is B: 23 autosomes. The ovule contains half the number of chromosomes as the typical somatic cell, which is 46 in humans. This is because during meiosis, the number of chromosomes is reduced by half to ensure the correct chromosome number in the offspring. Therefore, the ovule contains 23 chromosomes, which are autosomes (non-sex chromosomes). Choices A, C, and D are incorrect because the ovule does not contain the same number of somatic chromosomes, a sex chromosome, or 11 pairs of somatic chromosomes.