Question 1 CAM plants have adapted to very dry climates by o

Question 1. CAM plants have adapted to very dry climates by opening their stomata only during the day.

True

False

2 points   

QUESTION 2

If the haploid number of chromosomes in an organism is 16, then the diploid number is

24

4

8

32

2 points   

QUESTION

In human blood groups, the A, B, and O alleles are codominant.

True

False

2 points   

QUESTION

If two plants that show incomplete dominance are crossed, one having red flowers and the other pink flowers, what will be the phenotypic ratio of their offspring?

1 pink:2 white:1 red

1 red:2 pink:1 white

1 white:2 red:1 pink

2 red:2 pink

2 points   

QUESTION

DNA transcription takes place in the nucleus.

True

False

2 points   

QUESTION

Which of the following is not haploid?

sperm

gamete

zygote

egg

		24
		4
		8
		32

Solution

Ans. 1. False

CAM plants are adapted to very dry climates by opening their stomata during the night. Night temperature is relatively much lower than that of the day time. So, opening stomata during night time cause less evaporation (low loss of water) loss of water during transpiration than day time.

Ans. 2. True.

Alleles are said to be co-dominant when both alleles are expressed simultaneously in heterozygous condition and both the traits retain their identity. For example, in AB blood group, both the antigens A (gene product of allele I^A) and B (gene product of allele I^B) are simultaneously expressed and independently present on RBC cell surface.

In a complete dominance scenario, only the dominant allele is expressed while the recessive is NOT expressed in heterozygous condition.

Ans. 3. Incomplete dominance shows simultaneously expression of two alleles in the heterozygous condition, but the two traits blend together to give a new phenotype.

Consider the difference of crosses between homozygous red and homozygous white flower as RR x rr = RR, Rr, Rr, rr. -

I. Complete dominance: Rr progeny = red flower as that of dominant allele.

II. Incomplete dominance: Rr progeny = Pink flower as blending of red and white color because R and r are expressed simultaneously.

III. Co-dominance: Rr progeny = A flower with white and red patches of color- both R and r are expressed simultaneously and both the phenotypes retain their identity.

Now, coming to the question-

Genotype of homozygous red flower: RR

Genotype of homozygous red flower: Rr

Now,

            RR x Rr = RR, Rr                   ; [RR = red      ; Rr = pink]

            Phenotype ratio = 1: 1 or 2: 2 or 3:3   ; [Note: multiplying a ratio with any factor does not affect the ration. SO, 1:1 = 2: 2 = 3: 3, and so on].

Ans. 4. True

DNA transcription i.e. formation of RMA from DNA is called transcription. Because DNA is present in nucleus and does not come out in cytoplasm at any point, the transcription must occur in nucleus.

Ans. 5. Correct option C. zygote.

Sperm (n) + egg (n) -------> Zygote (2n). Fusion of egg with sperm gives diploid zygote.

Sperm and egg are gametes- all being haploid (n).