In a oak hickory forest in Pennsylvania, gray squirrel populations have been declining due to increased predation by hawks and o
ther predators. At the same time, researchers have discovered that the average thickness of acorns in the forest have decreased by 15% due to lower feeding pressure from squirrels. What type of natural selection would this be an example of?
directional T/F
directional T/F
2 answers:
Answer:
Directional -------- TRUE ✔
Explanation:
Directional selection is a kind of natural selection that as the phenotype (the observable characteristics) of the species moving towards an extreme instead of the mean phenotype or the other extreme phenotype.
This type of selection is observed in environments that experienced variation over time as in weather, climate, or food availability. It gives a population bell curve for a certain trait that moves either in the left or right direction as seen in the attached image.
It is important to note that animal predators can also lead to directional selection as the slower animals in a prey population tends to be killed and eaten as the directional selection will continually skew the population in the direction of the faster animals.
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Answer:
5. The correct answer would be an option A. ova
Note: I assume that all the samples are of human origin.
DNA (deoxyribonucleic acid) content of somatic cells of humans consists of 46 chromosomes or 23 pairs of chromosomes. Gametes (sperm or ova) are haploid cells produced by the process of meiosis and contain half the number of chromosomes found in parent cell. Hence, they contain 23 chromosomes.
6. The correct answer would be an option J.
Sperm formation or spermatogenesis is the process by which spermatozoa (haploid gamete) is produced from germ cell with the help of meiotic division.
Meiosis results in the formation of four haploid (n) cells from single diploid (2n) parent cell. Here, 2n is given as 8 so, n would be equal to 4.
Meiosis I results in the formation of two secondary spermatocyte cells (both haploid or 4 chromosomes in this case) from single primary spermatocyte (diploid or 8 chromosome in this case).
Both the secondary spermatocytes undergo meiosis II to produce 4 spermatids (each haploid or 4 chromosome in this case). Spermatids differentiate and mature into spermatozoa.
