ati teas 7 science

Correct Answer: D

Rationale: The correct answer is D because chromosomal nondisjunction can lead to various genetic disorders such as Down syndrome (A), caused by an extra chromosome 21. Nondisjunction can also result in Turner syndrome (B) in females due to the absence of one X chromosome, and Klinefelter syndrome (C) in males with one or more extra X chromosomes. Therefore, all the options are potential consequences of chromosomal nondisjunction.

Correct Answer: B

Rationale: The correct answer is B: Nucleotide. Nucleotides are the building blocks of DNA, consisting of a sugar molecule, a phosphate group, and a nitrogenous base. They are linked together in a specific sequence to form the DNA molecule's double helix structure. Amino acids (choice A) are the building blocks of proteins, not DNA. Phosphate groups (choice C) are components of nucleotides but are not the sole building blocks of DNA. Fatty acids (choice D) are not involved in the structure of DNA at all. Therefore, the correct answer is nucleotide as it accurately represents the basic components that make up DNA.

Correct Answer: B

Rationale: The correct answer is B: Acting as a protective sac surrounding the heart. The pericardium is a double-walled sac that surrounds and protects the heart. It provides physical protection against external forces and prevents overfilling of the heart. Choices A, C, and D are incorrect as they do not accurately describe the function of the pericardium. Choice A refers to the role of heart valves, choice C refers to the role of the heart's electrical system, and choice D refers to the function of the atrioventricular node.

Correct Answer: C

Rationale: The correct answer is C: Luteinizing hormone (LH). LH surge triggers ovulation by causing the mature ovarian follicle to release the egg. Estrogen and progesterone play important roles in regulating the menstrual cycle but are not the primary triggers for ovulation. FSH stimulates the growth of ovarian follicles but does not directly trigger ovulation.

Correct Answer: A

Rationale: The correct answer is A: Convergent evolution. Dinosaurs evolving feathers before birds supports convergent evolution because it shows unrelated organisms (dinosaurs and birds) developing similar traits (feathers) independently to adapt to similar environmental pressures. This scenario is not an example of divergent evolution (B) where related organisms evolve different traits. It also does not demonstrate coevolution (C) where two species influence each other's evolution. The extinction of dinosaurs due to an asteroid impact (D) is not directly related to the evolution of feathers in dinosaurs before birds.