Multiple Choice QuestionsPure tall plants are crossed with pure dwarf plants. In the F1 generation, all plants were tall. These tall plants of F1 generation were selfed and the ratio of tall to dwarf plants obtained was 3 : 1. This is called
dominance
inheritance
codominance
heredity
The trisomy for 21st chromosome is called
Down's syndrome
Turner's syndrome
Sickle cell anaemia
Klinfelter's syndrome
A.
Down's syndrome
| Abnormality | Cause | Characteristic |
| Down's Syndrome | Trisomy of 21st chromosome (45 A + XX/ XY) | Mental retardation, prominent head, flattened nasal bridge, open mouth, short stature etc |
| Turner's Syndrome | Non- disjunction of sex chromosome (2n = 45; 44A +XO) | Sterile female, webbed neck, no breast development, no menstruation or egg production |
| Klinefelter's Syndrome | Non- disjunction of sex chromosomes (2n = 47; 44A + XXY) | Sterile male with low IQ, testes underdeveloped. |
| Sickle cell anaemia | Molecular gene mutation of gene HbA | Sickle shaped RBCs, do not transport O2 efficiently |
If root of a flowering plant has 24 chromosomes, then its gamete has how many chromosomes?
24
12
4
8
Balbiani rings are the structural features of
allosomes
polytene chromosomes
autosomes
Lampbrush chromosomes
X- linked recessive gene is
always expressed in male
always expressed in femlae
lethal
sub- lethal
1 : 2 : 1 phenotypic and genotypic ratio is found in
complementary genes
blending inheritance
multiple alleles
pseudo alleles
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