In plant physiology, the 'Senescence' refers to the process of: MCQ with Answer and Explanation

In plant physiology, the 'Senescence' refers to the process of:
A. Rapid cell division
B. Aging and programmed death of plant organs or the whole plant
C. Seed germination
D. Flower opening
Answer: Option B
Solution (By JKExamLibrary)
Senescence in plants is the biological process of aging, culminating in the structured, programmed death of plant organs (like leaves, flowers, or fruits) or the entire plant. It involves the coordinated breakdown of macromolecules (proteins, nucleic acids, chlorophyll) and the mobilization of nutrients (like nitrogen and phosphorus) from the senescing organ to other growing parts of the plant (like developing seeds). It is a highly regulated process influenced by hormones like ethylene and abscisic acid, and delayed by cytokinins.

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Practice More Biology Questions

Question #1
The hormone that lowers blood calcium by depositing it in bones is:
A. Parathyroid hormone
B. Thyroxine
C. Insulin
D. Calcitonin

Correct Answer: Option D


Explanation:
Calcitonin, secreted by the thyroid gland, reduces blood calcium by inhibiting osteoclast activity and promoting calcium deposition in bones. Parathyroid hormone raises calcium. Thyroxine regulates metabolism, insulin lowers blood glucose.

This question belongs to: Science Biology
Question #2
Which endocrine gland is known as the 'master gland'?
A. Pituitary
B. Adrenal
C. Thyroid
D. Pancreas

Correct Answer: Option A


Explanation:
The pituitary gland, located at the base of the brain, controls other endocrine glands through its hormones (e.g., TSH, ACTH, FSH, LH). Hence, it is called the master gland. The hypothalamus regulates the pituitary via releasing and inhibiting hormones. Thyroid secretes thyroxine, adrenal secretes adrenaline, pancreas (endocrine part) secretes insulin and glucagon. The pituitary has two lobes: anterior and posterior.

This question belongs to: Science Biology
Question #3
The plant tissue responsible for growth in length is:
A. Lateral meristem
B. Sclerenchyma
C. Apical meristem
D. Cambium

Correct Answer: Option C


Explanation:
Apical meristems at root and shoot tips undergo cell division, causing primary growth (increase in length). Lateral meristems increase girth.

This question belongs to: Science Biology