Which of the following statements about prokaryotic cells is INCORRECT? MCQ with Answer and Explanation

Which of the following statements about prokaryotic cells is INCORRECT?
A. Their genetic material is circular DNA.
B. They contain membrane-bound organelles.
C. They possess 70S ribosomes.
D. They lack a well-defined nucleus.
Answer: Option B
Solution (By JKSSB Mock Tests)
Prokaryotic cells lack membrane-bound organelles such as mitochondria, ER, Golgi, etc. They have a nucleoid region, 70S ribosomes, and typically a single circular chromosome. Thus, the statement that they contain membrane-bound organelles is incorrect.

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Practice More Biology Questions

Question #1
Which of the following statements about genetics is correct?
A. Homozygous individuals have two different alleles for a trait.
B. A monohybrid cross gives a phenotypic ratio of 9:3:3:1.
C. Mendel’s law of segregation states that allele pairs separate during gamete formation.
D. Phenotype refers to the genetic makeup of an organism.

Correct Answer: Option C


Explanation:
Mendel’s first law (segregation) states that the two alleles for a trait separate during gamete formation. Homozygous individuals have identical alleles; phenotype is observable trait; a monohybrid ratio is 3:1.

This question belongs to: Science Biology
Question #2
The rearing of silkworms for silk production is known as:
A. Vermiculture
B. Pisciculture
C. Apiculture
D. Sericulture

Correct Answer: Option D


Explanation:
Sericulture involves the cultivation of mulberry plants (Morus alba) and rearing of the silkworm Bombyx mori to produce raw silk. Apiculture is beekeeping, pisciculture is fish farming, vermiculture is earthworm rearing for compost. India is the second-largest producer of silk after China, producing mulberry, tasar, eri, and muga silk.

This question belongs to: Science Biology
Question #3
Assertion (A): Mitochondria and chloroplasts are considered semi-autonomous organelles. Reason (R): They possess their own DNA and ribosomes, and can synthesize some of their own proteins.
A. A is false, but R is true.
B. A is true, but R is false.
C. Both A and R are true, and R is the correct explanation of A.
D. Both A and R are true, but R is not the correct explanation of A.

Correct Answer: Option C


Explanation:
Mitochondria and chloroplasts contain circular DNA and 70S ribosomes, enabling them to transcribe and translate some proteins independently, though they rely on nuclear genes for most proteins. This partial autonomy supports the endosymbiotic origin hypothesis. The presence of their own genetic material and protein synthesis machinery qualifies them as semi-autonomous. Thus, both assertion and reason are correct, and the reason correctly explains the assertion.

This question belongs to: Science Biology