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Cells are created from existing cells is the part of the cell theory which explains why the skin is able to repair itself. The body produces 300 million new cells every day. After getting a cut or scratch, the skin may start bleeding. This happens when the injury tears down the tiny blood vessels that is found under the skin’s surface. The body wants to stop the bleeding so the platelets will come to the rescue.

At the cut, platelets stick together. This is how the blood clots which then become a scab. This protects the area so the cells underneath it can have the time to heal. Beneath the scab, new skin cells multiply to repair the wound. Damaged blood vessels are restored and blood cells end the infection in the wound. And also, under the scab, a new skin layer is formed.

6 0

3 years ago

In Drosophila, an autosomal gene determines the shape of the hair, with B giving straight and b giving bent hairs. On another au

klasskru [66]

Answer:

a. F1 genotype : IiBb F1 phenotype : Hairless

F2 genotype and phenotype :

I_B_ (hairless), iiB_ (straight), iibb (bent)

b. IiBb X iiBb

Explanation:

a. Fly 1 : pure breeding straight haired : iiBB

Fly 2 : pure breeding hairless with bent genotype : IIbb

Fly 1 X Fly 2 : iiBB X IIbb = IiBb (F1)

All the offspring will be hairless since there is one dominant I allele which will inhibit hair production regardless of the type of allele of other gene.

Two F1 flies will be crossed to obtain F2 flies. IiBb X IiBb :

I_B_ : hairless = 9

I_bb : hairless = 3

iiB_ : straight hair = 3

iibb : bent hair = 1

Hairless : straight : bent will be in 12 : 3 : 1 ratio.

b. The offspring of this cross :

hairless : I_ _ _

straight : iiB_

bent : iibb

There is a bent offspring which has both the recessive alleles of both the genes. Hence it must have obtained the two alleles from the two parents. So their genotype is _i_b and _i_b.

Half of the offspring are hairless as given by the ratio. This is only possible if the cross is between Ii and ii fly:

I i

i Ii ii

So the genotype is Ii_b and ii_b.

The remaining hairy flies are in 3:1 ratio of straight to bent. This is only possible if the cross is between Bb and Bb fly:

B b

B BB Bb

b Bb bb

So the final genotype of the flies is IiBb and iiBb.

4 0

4 years ago

The enforcement of hunting regulations are conservation measures that promote the A. use of biological controls. B. fur industry

sdas [7]

Answer:

the answer is D: the the preservation of species

Explanation:

3 0

3 years ago

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