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Heredity and Variation Class 12. We covered all the Heredity and Variation Class 12 in this post for free so that you can practice well for the exam.
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mcq on Heredity and Variation Class 12 for NEET Students
What type of genetic disorder is sickle cell anemia?
(a) Autosomal recessive condition
(b) Recessive disorder linked to sex chromosomes
(c) Condition arising due to aneuploidy
(d) Autosomal dominant trait
Option a – Autosomal recessive condition
Choose the correct option based on the following:
Statement I: The principle of independent assortment suggests that the separation of one pair of genes is unaffected by the separation of another pair during hybrid formation.
Statement II: The law of segregation implies that traits do not blend and both reappear in the F₂ generation, even if only one is visible in F₁.
(a) Only Statement I is correct
(b) Only Statement II is correct
(c) Both statements are correct
(d) Both statements are incorrect
Option c – Both statements are correct
Which of the following statements about honey bees is inaccurate?
(a) Both worker and queen bees originate from fertilized eggs
(b) Male bees are haploid, while females are diploid
(c) Males produce sperm cells through meiosis
(d) Worker bees are females, while drones are males
Option c – Males produce sperm cells through meiosis
A woman with blood group O has a child with the same blood group. The father’s blood group can be
(a) A
(b) B
(c) O
(d) Any of the above
Option d – Any of the above
Which statement about Klinefelter’s syndrome is not true?
(a) It results in males with feminized traits
(b) It occurs due to loss of an X chromosome
(c) Affected individuals may develop enlarged breasts
(d) Individuals with this condition are infertile
Option b – It occurs due to loss of an X chromosome
What would be the outcome when Aa is crossed with aa?
(a) Half the offspring will express the dominant trait, the other half recessive
(b) All offspring will express the dominant trait
(c) All will express the recessive trait
(d) Three-fourths will be dominant and one-fourth recessive
Option a – Half the offspring will express the dominant trait, the other half recessive
Which of the following exhibits pleiotropic effects?
(a) Thalassemia
(b) Phenylketonuria
(c) Haemophilia
(d) All of the above
Option b – Phenylketonuria
Choose the one that is not classified as a Mendelian disorder.
(a) Thalassemia
(b) Haemophilia
(c) Colour blindness
(d) Cushing’s syndrome
Option d – Cushing’s syndrome
Crossing a red-flowered and a white-flowered pea plant yields hybrids that appear different from both parents. What genotypic ratio will appear in F₂?
(a) 3:1
(b) 1:2:1
(c) 9:3:3:1
(d) 3:1:2
Option b – 1:2:1
Which of the following is not an intragenic interaction?
(a) Incomplete dominance
(b) Co-dominance
(c) Pleiotropy
(d) Multiple alleles
Option c – Pleiotropy
What is the function of a pleiotropic gene?
(a) Affects a single trait
(b) Influences multiple phenotypes
(c) Suppresses another gene at a different locus
(d) Prevents recombination
Option b – Influences multiple phenotypes
What proportion of the F₂ generation shows the recessive trait in a monohybrid cross?
(a) 25%
(b) 50%
(c) 75%
(d) 100%
Option a – 25%
Which of these is a case of monosomy?
(a) Turner syndrome
(b) Down syndrome
(c) Klinefelter syndrome
(d) None of the above
Option a – Turner syndrome
Identify the dominant trait studied by Mendel in pea plants.
(a) White flowers
(b) Constricted pods
(c) Wrinkled seeds
(d) Inflated pods
Option d – Inflated pods
In Antirrhinum, the hybrid between red (RR) and white (rr) produces pink (Rr) flowers. This is an example of
(a) Co-dominance
(b) Incomplete dominance
(c) Complete dominance
(d) Pleiotropy
Option b – Incomplete dominance
In which organism are males homogametic?
(a) Birds
(b) Humans
(c) Grasshoppers
(d) Drosophila
Option a – Birds
Choose the correct statements:
i. Haemophilia is a sex-linked recessive condition
ii. Down syndrome results from monosomy of X
iii. Phenylketonuria is caused by an autosomal recessive gene
iv. Thalassemia is inherited if both parents are carriers
(a) i and ii
(b) ii and iv
(c) i, ii, and iii
(d) i, iii, and iv
Option d – i, iii, and iv
Crossing a tall, red-flowered homozygous plant with a dwarf, white-flowered homozygous plant results in offspring that are tall and red. What is their genotype?
(a) TtRr
(b) TTRR
(c) TTRr
(d) ttrr
Option a – TtRr
Which type of sex determination occurs in birds?
(a) ZZ-ZW
(b) XX-XY
(c) Haplodiploidy
(d) XO
Option a – ZZ-ZW
Identify the incorrect statement about back crosses.
(a) In a recessive back cross, F₁ is crossed with the recessive parent
(b) A dominant back cross yields all dominant phenotypes
(c) A back cross is always a dominant back cross
(d) Not all back crosses are test crosses
Option a – In a recessive back cross, F₁ is crossed with the recessive parent
How many distinct gametes can be formed by an organism with genotype AABbCc?
(a) 4
(b) 2
(c) 9
(d) 8
Option a – 4
We covered all the Heredity and variation Class 12 above in this post for free so that you can practice well for the exam.
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