The phenomenon where the primary root is short-lived and is replaced by a cluster of roots arising from the base of the stem is seen in: MCQ with Answer and Explanation

The phenomenon where the primary root is short-lived and is replaced by a cluster of roots arising from the base of the stem is seen in:
A. Mustard
B. Peepal tree
C. Carrot
D. Grasses
Answer: Option D
Solution (By JKSSB Mock Tests)
In monocotyledonous plants like grasses, the primary tap root formed from the radicle is short-lived and aborts early. It is subsequently replaced by a large number of fibrous roots that arise adventitiously from the base of the stem. This forms a fibrous root system. Mustard, peepal, and carrot exhibit a tap root system derived from the primary root.

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Practice More Biology Questions

Question #1
Which of the following is an example of a genetically engineered insulin-producing bacterium?
A. Bacillus subtilis
B. Escherichia coli
C. Saccharomyces cerevisiae
D. Pseudomonas aeruginosa

Correct Answer: Option B


Explanation:
Recombinant human insulin (Humulin) is produced by genetically engineered Escherichia coli (or yeast) carrying the human insulin gene. Before this, insulin from animal sources was used. The A and B chains of insulin are produced separately and then combined. This was the first genetically engineered pharmaceutical approved for human use (1982).

This question belongs to: Science Biology
Question #2
The enzyme Taq polymerase, used in PCR, is obtained from:
A. Thermus aquaticus
B. Escherichia coli
C. Agrobacterium tumefaciens
D. Salmonella typhimurium

Correct Answer: Option A


Explanation:
Taq polymerase is a thermostable DNA polymerase enzyme isolated from the thermophilic bacterium Thermus aquaticus, found in hot springs. It is used in the Polymerase Chain Reaction (PCR) because it can withstand the high temperatures (around 94°C) required for the denaturation step of PCR without being destroyed, unlike normal DNA polymerases.

This question belongs to: Science Biology
Question #3
The pacemaker of the heart is the:
A. Sinoatrial node
B. Bundle of His
C. Purkinje fibers
D. Atrioventricular node

Correct Answer: Option A


Explanation:
The SA node, located in the right atrium, spontaneously generates electrical impulses, setting the heart rate. It is the natural pacemaker. The AV node delays the impulse before it reaches the ventricles.

This question belongs to: Science Biology