Answer: The frequency of brown beetles is 0.32.
Explanation: The frequency of A1 allele is 0.8. As p+q=1, or the sum of dominant and recessive frequencies equals 1 or 100%:
1 - 0.8 = 0.2
In Hardy-Weinberg principle,

2pq represents the frequency of heterozygote individuals, so:
genotype A1A2 = 2*0.8*0.2 = 0.32.
Thus, the frequency of brown beetles (A1A2) in the population is 0.32.
Answer: Alveoli
Explanation: Alveoli of lungs are surrounded by extensive blood capillaries. The partial pressure of oxygen in the alveoli is higher than the blood entering the pulmonary capillaries, hence oxygen moves into the blood. Carbon dioxide in the lungs simultaneously diffuse out of the blood into the alveolar space.
Answer:
True
Guard cells close openings in the leaves slowing down water loss.
Answer:
Replication, transcription, translation (it’s the central dogma of biology)