Correct Answer: C

Rationale: Metabolic wastes produced by the developing fetus are eliminated primarily by being passed down the umbilical cord to the mother's circulatory system. Once in the mother's blood, these wastes are then filtered and excreted by the mother's kidneys. Choice A is incorrect because the developing fetus does produce metabolic wastes. Choice B is incorrect as fetal waste does not pass into the mother's anus. Choice D is incorrect as fetal waste does not leave the mother's body via the vagina.

Correct Answer: B

Rationale: The ribcage is the correct answer. It protects the lungs by providing structural support and shielding them from injury. The femur is a bone in the thigh and does not protect the lungs. The scapula is a shoulder blade bone, and the skull protects the brain, not the lungs.

Correct Answer: D

Rationale: The correct answer is Oxygen. Oxygen has a total of 8 electrons, with 2 in the first shell and 6 in the second shell. This configuration matches the description provided in the question. Choice A, Beryllium, has 2 electrons in total, so it cannot have 2 in the first shell and 6 in the second. Choice B, Carbon, has 6 electrons in total, so it also does not match the given electron distribution. Choice C, Helium, has only 2 electrons in total and therefore does not fit the electron configuration described in the question.

Correct Answer: A

Rationale: The correct order of cellular respiration is Glycolysis, Acetyl-CoA, Citric Acid Cycle, and Electron Transport Chain. Glycolysis initiates the breakdown of glucose in the cytoplasm, leading to the formation of pyruvate. This pyruvate is then converted to Acetyl-CoA in the mitochondria, which enters the Citric Acid Cycle to generate energy-rich molecules like NADH and FADH2. Finally, the Electron Transport Chain, located in the inner mitochondrial membrane, utilizes these energy carriers to produce ATP through oxidative phosphorylation. Choice B is incorrect because it starts with the Citric Acid Cycle, which comes after Glycolysis. Choice C is incorrect as it places the Citric Acid Cycle before the Electron Transport Chain. Choice D is incorrect by placing Acetyl-CoA last instead of before the Citric Acid Cycle.

Correct Answer: A

Rationale: Chiasmata structures, where crossing over occurs, form during Prophase I of meiosis. This phase is characterized by homologous chromosomes pairing up and crossing over, leading to the exchange of genetic material between non-sister chromatids. Chiasmata are visible points of contact where genetic material has been exchanged, and they play a critical role in genetic diversity. Prophase II is the phase where chromosomes condense again in the second meiotic division, but chiasmata formation occurs in Prophase I. Metaphase I is the phase where homologous chromosomes align at the metaphase plate, not where chiasmata form. Metaphase II is the phase where replicated chromosomes align at the metaphase plate in the second meiotic division, but chiasmata formation occurs earlier in Prophase I.