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408 questions in this collection · Page 21 of 41
Sexual Reproduction In Flowering Plants
Sexual Reproduction In Flowering Plants
Sexual Reproduction In Flowering Plants
AI-generated explanation. Check against your textbook.
The phrase “two generations - one within the other” refers to a gametophyte (haploid generation) developing inside the sporophyte (diploid) structure. Pollen grains contain the male gametophyte inside the anther, and embryo sac (within the ovule) contains the female gametophyte. Both A (pollen grains inside the anther) and D (embryo sac inside the ovule) represent the gametophytic generation inside the sporophytic tissue, as described in NCERT. B is about a germinated pollen grain producing two male gametes, which is about development inside a pollen tube, not a separate generation within a structure. C (seed inside the fruit) involves a sporophyte embryo inside a seed, not a separate gametophyte generation within another structure.
In angiosperms, the flowering plant body (sporophyte) surrounds the gametophytes found inside the pollen grain and the ovule.
Gametophyte generation is found inside the sporophyte in both pollen grain and embryo sac.
Principles Of Inheritance And Variation
Principles Of Inheritance And Variation
AI-generated explanation. Check against your textbook.
The wrong statement is option 3. In the ABO system, IA and IB are codominant; when both are present (IAIB), the person has AB blood type with both A and B antigens. The statement says they express the same sugar, which is incorrect because A and B antigens are different sugars on RBC surfaces.
Allele i is recessive and does not code for A or B antigens; individuals with ii blood type have no A or B antigens (O blood group).
The gene I has three alleles (IA, IB, i); a person carries two alleles, and IA and IB show codominance to yield AB type when present together.
Principles Of Inheritance And Variation
Principles Of Inheritance And Variation
AI-generated explanation. Check against your textbook.
Option 3 is correct. Sickle cell anaemia is an autosomal recessive disorder caused by a mutation in the beta-globin gene on chromosome 11. Children must inherit two faulty copies to express the disease. Options 1, 2 and 4 are incorrect according to NCERT: haemophilia is X-linked recessive (not Y-linked); phenylketonuria is autosomal recessive (not dominant); thalassemia is also autosomal recessive (not X-linked).
Carriers (heterozygotes) for sickle cell trait usually do not show full disease but may have some abnormal Hb; this trait is more common in populations where malaria is or was prevalent.
“Sickle cell anaemia is an autosomal recessive disorder due to mutation in beta-globin gene on chromosome 11.”
Principles Of Inheritance And Variation
Principles Of Inheritance And Variation
Principles Of Inheritance And Variation
AI-generated explanation. Check against your textbook.
The best example of pleiotropy is Phenylketonuria (PKU). In pleiotropy, a single gene affects many traits. The PKU gene causes a deficiency of the enzyme phenylalanine hydroxylase, leading to accumulation of phenylalanine and affecting multiple body processes. This results in various problems such as intellectual disability, growth issues, and other metabolic effects, illustrating one gene influencing several traits.
NCERT discusses pleiotropy with examples like PKU to show how a single gene mutation can impact more than one phenotype.
Pleiotropy: one gene, many effects.