Download App

Molecular Basis of Inheritance — BIOLOGY STD 12 Science — Question

Maharashtra BoardEnglish MediumSTD 12 ScienceBIOLOGYMolecular Basis of Inheritance1 Mark
MCQ
For question, two statements are given$-$one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion: $R-$type of Pneumococcus is non$-$virulent.
Reason: $R-$type of Pneumococcus can be virulent by having transformation with $S -$type of Pneumococcus.
  • A
    Both assertion and reason are true, and reason is the correct explanation of assertion.
  • ✓
    Both assertion and reason are true, but reason is not the correct explanation of assertion.
  • C
    Assertion is true, but reason is false.
  • D
    Both assertion and reason are false.
✓

Answer

Correct option: B.
Both assertion and reason are true, but reason is not the correct explanation of assertion.
Transformation is the change in the genetic constitution of an organism by picking up genes present in the environment. Pneurnococcus has two strains $-$virulent $(S)$ and non$-$virulent $(R).$ The virulent strain causes pneumonia. $R-$type bacteria form irregular or rough colonies and did not produce any disease while the $S-$type bacteria cause pneumonia and then death in the mice. Griffith injected a combination of live $R-$type and heat killed $S-$type bacteria into mice. While some mice survived, others developed the disease of pneumonia and died. Autopsy of the dead mice showed that they possessed both the types of bacteria in living state, though the mice had been injected with dead virulent and living non$-$virulent bacteria. The occurrence of living $S-$type virulent bacteria is possible only by their formation from $R-$type non$-$virulent bacteria, which pick up the trait of virulence from dead bacteria. The phenomenon is called transformation.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "Assertion (A) & Reason (B) MCQ" from Molecular Basis of Inheritance→Molecular Basis of Inheritance — all question types→BIOLOGY STD 12 Science question papers→Maharashtra Board STD 12 Science question papers→Maharashtra Board question paper generator→

Similar questions

For question two statements are given $-$ one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion : No two species can occupy the same ecological niche in a habitat.
Reason : A habitat can contain only one ecological niche.
→
For question two statements are given$-$one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion: Species diversity decreases as we ascend towards high mountains.
Reason: Due to drop in temperature, no seasonal variability occurs in high mountains.
→
For question two statements are given $-$ one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion : Alpha diversity is said to be higher if the dissimilarity between communities is higher.
Reason : Alpha diversity is a measure of diversity between the communities.
→
For question two statements are given$-$one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion: The soil profiles of grassland, forest and desert biomes differ from each other.
Reason: Soil profile develops due to weathering process, accumulation of organic matter and leaching of mineral matter.
→
Read the following and answer any four questions from $(i)$ to $(v)$ given below:
The endosperm makes the main source of food for the embryo. Generally the endosperm nucleus divides after the division of the oospore, but in several cases the endosperm is formed to a great extent even before the first division of the oospore. There are three general types of endosperm formation: $(a)$ nuclear type, $(b)$ cellular type and $(c)$ helobial type. The endosperm is usually triploid, but haploid endosperm is also found. Endosperm may either be completely consumed by the developing embryo before seed maturation, or it may persist in the mature seed.
  1. Haploid endosperm is found in :
  1. Pin us.
  2. Cauliflower.
  3. Sunflower.
  4. Pea.
  1. Persistent endosperm is found in:
$P$. Pea $Q$. Castor $R$. Bean $S.$ Coconut $T$. Groundnut.
  1. $Q$ and $S$.
  2. $P$ and $T$.
  3. $R, S$ and $T$.
  4. $P, S$ and $T$.
  1. Milk of tender coconut represents $(A)$ and the surrounding white coconut meal represents $(B).$
S. No
$A$
$B$
$(a)$
Cellular endosperm
Free- nuclear endosperm
$(b)$
Free $-$ nuclear endosperm
Cellular endosperm
$(c)$
Helobial endosperm
Cellular endosperm
$(d)$
Free-nuclear endosperm
Helobial endosperm
  1. If an endosperm cell of a gymnosperm contains $12$ chromosomes, the number of chromosomes in each cell of the root will be:
  1. $4$
  2. $24$
  3. $16$
  4. $6$
  1. In angiosperms, normally after fertilization:
  1. The zygote divides earlier than the primary endosperm nucleus.
  2. The primary endosperm nucleus divides earlier than the zygote.
  3. Both the zygote and primary endosperm nucleus divide simultaneously.
  4. Both the zygote and primary endosperm nucleus undergo a resting period.
→
For question, two statements are given$-$one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion : Immunity means all capacity of human body to resist almost all types of organisms or toxins that tend to damage the tissues and organs.
Reason: Spleen is the only organ involved in immunity.
→
For two statements are given$-$one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion: Nucellus functions as a nutritive tissue.
Reason: Nucellus is always exhausted completely during development of embryo sac.
→
For question two statements are given$-$one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion: Mendel was successful in his hybridisation experiments.
Reason: Garden pea proved to be an ideal experimental material.
→
Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion: In ripening of cheese, insoluble proteins are cleaved to form soluble peptides.
Reason: Hard cheese and soft cheese, both are ripened by lactic acid bacteria. 
→
For question two statements are given$-$one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion : Some diseases that attack in childhood do not attack again.
Reason: Memory cells plays an important role.
→