Question 17 Red flowers (R) are dominant to orange flowers (r), and tall (T) is

Question

Question 17

Red flowers (R) are dominant to orange flowers (r), and tall (T) is dominant to short (t) in a species of wild roses. A pure-breeding plant that is tall with red flowers is crossed with a pure-breeding plant that is short with orange flowers. What is the genotype of the F1 progeny?

RRTT

RrTT

RRTt

RrTt

Rrtt

1 points

Question 18

In Mendel's peas, yellow seeds are dominant to green. A pure-breeding yellow plant is crossed with a pure-breeding green plant. All of the offspring are yellow. If one of these yellow offspring is crossed with a green plant, what will be the expected proportion of plants with green seeds in the next generation?

0%

25%

50%

75%

100%

1 points

Question 19

If an organism of genotype Aa is used for a testcross, what is the genotype of the other individual used in the cross?

AA

Aa

aa

Either AA or Aa are possible.

The genotype cannot be determined.

1 points

Question 20

Mendel's law of _____________ states that the random sorting of maternally and paternally derived chromosomes during meiosis results in gametes with genetic variation.

dominance

segregation

independent assortment

all of the above

none of the above

RRTT

RrTT

RRTt

RrTt

Rrtt

Explanation / Answer

17. The genotype of pure breeding tall red flowered plant is RRTT and that of short orange flowered is rrtt. The RRTT plant will produce only one type of gamete RT and rrtt will produce only one type of gamete rt. The fusion of RT with rt will result in F1 with RrTt. So option 4 is correct.

18. The yellow seed plant will have YY genotype and green seed plant will have yy genotype. The F1 plants have yellow seeds with genotype Yy. When Yy plant is crossed green(yy) plant, the progeny will be of two types - 50% Yy (yellow) and 50% yy (green). So option no. 3 is correct.

19. In a test cross, if one organisms has Aa genotype then the other organism must be homozygous recessive with genotype aa. So, the option no. 3 is correct.

20. As per Mendel's law of independent assortment, the alleles of differnt genes present on the paternally and maternally derived chromosomes undergo independent assortment. So, the correct option is no. 3.

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