Inheritance and Variation MCQs

Q1. Consider the following statements about inheritance and variation: (I) Genes are units of heredity. (II) Variation arises mainly in sexual reproduction. (III) Acquired traits are always inherited. Which of the above statement(s) is/are correct?

• A.Only I
• B.Only I and II
• C.Only III
• D.None of these

Answer: B. Only I and II

To see why, recall that An ionic bond forms when a metal donates electrons to a non-metal: e.g. Na -> Na+ + e-, Cl + e- -> Cl-, and Na+ + Cl- -> NaCl; the resulting solid is held by strong electrostatic attraction => this fixes the property asked in the stem; hence the answer = Only I and II. That fits the listed correct option directly - Correct. Looking at the others: option A) 'Only I' is incorrect: Re-check each statement individually; option C) 'Only III' fails since Re-check each statement individually. Hence the answer is B) Only I and II.

Q2. The unit of inheritance that controls a trait is the:

• A.ribosome
• B.cell wall
• C.vacuole
• D.gene

Answer: D. gene

From the stem we have: the data stated in the problem. Required: the unknown asked in the stem. Working tool - hence the answer = gene. This is the equation that links the given quantities to the unknown (biology, chapter 'Heredity'). What makes this the correct method - set up a Punnett square with the given parental genotypes. So the answer is D) gene. Wrong options at a glance: option A) 'ribosome' fails since Ribosomes make proteins; genes carry heredity; option B) 'cell wall' is incorrect: The cell wall supports plant cells, not heredity; option C) 'vacuole' doesn't hold - Vacuoles store substances, not heredity.

Q3. If a tall plant has the genotype Tt, its tallness is shown because T is:

• A.recessive to t
• B.dominant over t
• C.the same as t
• D.an acquired trait

Answer: B. dominant over t