OAT General Biology 5 — Questions and Answers
Question 1: Which of the following correctly describes the role of telomeres?
- They code for essential structural proteins
- They protect chromosome ends from degradation and fusion (Correct answer)
- They serve as origins of replication
- They contain centromere-binding proteins
Correct answer: They protect chromosome ends from degradation and fusion
Telomeres are repetitive non-coding DNA sequences that cap chromosome ends, preventing degradation and end-to-end chromosome fusions during each cell division.
Question 2: A species of insect evolves mimicry of a toxic species even though it is harmless. This is an example of:
- Müllerian mimicry
- Batesian mimicry (Correct answer)
- Aposematism
- Camouflage
Correct answer: Batesian mimicry
Batesian mimicry occurs when a harmless species evolves to resemble a harmful or toxic species, gaining protection from predators.
Question 3: Which layer of the skin contains melanocytes that produce melanin?
- Stratum corneum
- Stratum granulosum
- Stratum basale (Correct answer)
- Stratum spinosum
Correct answer: Stratum basale
Melanocytes are located in the stratum basale (deepest epidermal layer) and produce melanin that is transferred to surrounding keratinocytes for UV protection.
Question 4: What is the primary role of the corpus luteum after ovulation?
- Produce FSH to maintain the cycle
- Secrete progesterone to maintain the uterine lining (Correct answer)
- Trigger ovulation of additional eggs
- Produce estrogen to thicken the endometrium
Correct answer: Secrete progesterone to maintain the uterine lining
The corpus luteum, formed from the ruptured follicle after ovulation, secretes progesterone (and some estrogen) to maintain the endometrium for potential implantation.
Question 5: Which of the following describes an r-selected species?
- Long lifespan, few offspring, high parental care
- Short lifespan, many offspring, little parental care (Correct answer)
- Large body size, low reproductive rate
- K-carrying capacity limited population
Correct answer: Short lifespan, many offspring, little parental care
r-selected species maximize reproductive rate (high r) by producing many offspring with minimal parental investment, thriving in unpredictable environments.
Question 6: Which process generates genetic diversity by exchanging segments between homologous chromosomes?
- Nondisjunction
- Translocation
- Crossing over (Correct answer)
- Independent assortment
Correct answer: Crossing over
Crossing over (recombination) occurs during prophase I of meiosis when non-sister chromatids of homologous chromosomes exchange corresponding segments at chiasmata.
Question 7: Which structure in the brain is most directly responsible for regulating homeostasis, hunger, and body temperature?
- Cerebellum
- Medulla oblongata
- Hypothalamus (Correct answer)
- Hippocampus
Correct answer: Hypothalamus
The hypothalamus is the master homeostatic regulator, controlling hunger, thirst, body temperature, circadian rhythms, and the release of pituitary hormones.
OAT General Biology 5
Which of the following correctly describes the role of telomeres?