Which statement is true about natural selection?

Biology

1 answer:

Alik [6]3 years ago

8 0

Answer:

I would say B

Explanation:

Because atural selection is the mechanism for how evolution occurs over time. Basically, natural selection says that individuals within a population of a species that have favorable adaptations for their environment will live long enough to reproduce and pass down those desirable traits to their offspring.

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What group of carbohydrates does glucose belong to ??

UNO [17]

Glucose belongs to Monosaccharides ....

8 0

3 years ago

The dominant allele H reduces the number of body bristles in fruit flies, giving rise to a hairless phenotype. In the homozygous

DerKrebs [107]

Answer:

a. 3:1 (normal bristles to hairless)

b. 2:1 (normal bristles to hairless)

Explanation:

a. If H allele is present, the fly will be hairless. But H allele is lethal at homozygous condition, so all hairless flies will be heterozygous for H locus (Hh). S allele has no effect on bristle number, but in presence of H allele, S produces a "normal" phenotype and is also lethal at the homozygous condition. So genotypes and phenotypes will be like this:

- SSHH: No viable- Lethal

- SSHh: No viable-Lethal

- SShh: No viable-Lehtal

- SsHH: No viable-Lethal

- SsHh: Normal

- Sshh: Hairless

- ssHH: Normal

- ssHh: Normal

- sshh: Normal

A cross between two normal flies carrying the two alleles (SsHh) will produce (according to the attached Punnett Square):

6 Normal (SsHh, ssHh, and sshh)

2 Hairless (Sshh)

Therefore, the ratio of flies with normal bristles to hairless individuals will be 3:1.

b. When the hairless progeny of the previous cross (Sshh) are crossed with one of the parental normal flies from part a (SsHh), it will be produced (according to the second Punnett Square):

8 Normal (SsHh, ssHh, and sshh)

4 Hairless (Sshh)

So, the ratio of flies with normal bristles to hairless individuals will be 2:1.