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3 years ago

Watson and Crick's model of DNA replication is called

Biology

1 answer:

alex41 [277]3 years ago

8 0

Answer:

(B) semiconservative.

Explanation:

According to the model proposed by Watson and Crick, the DNA molecule consists of two polynucleotide chains arranged on a helix around an imaginary axis, rotating to the right (a double helix). That is, the DNA molecule is in the shape of a spiral staircase, in which the "steps" are made up of nucleotide nitrogen bases and the "handrails" are covalently linked phosphate and sugar - so it is said that DNA is shaped like a helical ribbon. Also according to Watson and Crick DNA replication is semi-conservative, because each strand of DNA will give rise to another strand that will be complementary to its nucleotides.

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In chickens, comb shape is determined by genes at two loci (R, r and P, p). A walnut comb is produced when at least one dominant

Ivenika [448]

Answer and Explanation:

Available data:

Comb shape is determined by genes at two loci (R, r and P, p).

The walnut comb genotype is R_P_.

The rose comb genotype is R_pp.

The pea comb genotype is rrP_.

The single genotype is rrpp.

a. Walnut crossed with single produces 1 walnut, 1 rose, 1 pea, and 1 single offspring:

Parental) RrPp x rrpp

Gametes) RP Rp rP rp rp rp rp rp

Punnet Square) RP Rp rP rp

rp RrPp Rrpp rrPp rrpp

rp RrPp Rrpp rrPp rrpp

F1 phenotype: 25% walnut, 25% rose, 25% pea, and 25% single.

F1 genotype: 4/16 RrPp, 1/16 Rrpp, 4/16 rrPp, 4/16 rrpp.

b. Rose crossed with pea produces 20 walnut offspring.

Parental) RRpp x rrPP

Gametes) Rp Rp Rp Rp rP rP rP rP

Punnet Square) Rp Rp Rp Rp

rP RrPp RrPp RrPp RrPp

F1 phenotype: 100% walnut.

F1 genotype: 16/16 RrPp.

c. Pea crossed with single produces 1 single offspring.

This is not possible, because the pea genotype involves at least one dominant allele P. There are two possible crosses: rrPp x rrpp, which must produce half of the progeny pea and the other half single, or rrPP x rrpp which produce a whole pea progeny with no single offspring.

Parental) rrPp x rrpp

Gametes) rP rp rP rp rp rp rp rp

Punnet Square) rP rp rP rp

rp rrPp rrpp rrPp rrpp

rp rrPp rrpp rrPp rrpp

F1 phenotype: 50% pea, and 50% single.

F1 genotype: 8/16 rrPp, 8/16 rrpp.

d. Rose crossed with pea produces 2 walnut, 1 single, and 1 pea offspring.

This is not possible, because having one of the parents with a rose phenotype involves at least one R allele, which means that there must be rose phenotype in the progeny.

Parental) Rrpp x rrPp

Gametes) Rp Rp rp rp rP rP rp rp

Punnet Square) Rp Rp rp rp

rP RrPp RrPp rrPp rrPp

rP RrPp RrPp rrPp rrPp

rp Rrpp Rrpp rrpp rrpp

rp Rrpp Rrpp rrpp rrpp

F1 phenotype: 25% walnut, 25% rose, 25% pea, and 25% single.

F1 genotype: 4/16 RrPp, 1/16 Rrpp, 4/16 rrPp, 4/16 rrpp.

e. Rose crossed with single produces 31 rose offspring.

Parental) RRpp x rrpp

Gametes) Rp Rp Rp Rp rp rp rp rp

Punnet Square) Rp Rp Rp Rp

rp Rrpp Rrpp Rrpp Rrpp

F1 phenotype: 100% rose (31 individuals equal 100% of the progeny).

F1 genotype: 16/16 Rrpp.

f. Rose crossed with single produces 10 rose and 11 single offspring.

Parental) Rrpp x rrpp

Gametes) Rp Rp rp rp rP rP rp rp

Punnet Square) Rp Rp rp rp

rp Rrpp Rrpp rrpp rrpp

F1 phenotype: 50% rose, 50% single.

F1 genotype: 8/16 Rrpp, 8/16 rrpp.

3 0

3 years ago

Most cancer-causing air pollutants are found outdoors. a. True b. False

igor_vitrenko [27]

The answer is (A) as increasing risk of lung cancer is from increasing levels of exposure to outdoor air pollution and particulate matter

6 0

3 years ago

How many amino acids can a sequence of 24 DNA bases code for?

timurjin [86]

The answer your looking for is 20 Amino Acids.

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3 years ago

HELP! WILL GIVE BRANLIEST + EXTRA POINTS!

kow [346]

Answer:

i dont know but i think both

Explanation:

hope i helped

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3 years ago

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Meiosis guarantees that in a sexual life cycle, offspring will inherit one complete set of chromosomes (and their associated gen

insens350 [35]

Answer:

HEREDITY ONLY:

none

GENETIC VARIATION ONLY:

none

BOTH:

all

Explanation:

In all the organism that reproduce sexually, produced offspring are genetically varied. As this genetic variation continues, it also leads to hereditary evolution of organism through gene flow from one generation to other. Therefore, the processes of DNA replication, crossing over, chromosome separation and alignment etc. ensure flow of genes from one generation to the next. This does not happen in organisms reproducing asexually.

6 0

3 years ago