Consider statements about plant biology: 1. Xylem transports water upwards. 2. Phloem transports food bidirectionally. 3. Cambium is responsible for secondary growth. Which are correct? MCQ with Answer and Explanation
Consider statements about plant biology: 1. Xylem transports water upwards. 2. Phloem transports food bidirectionally. 3. Cambium is responsible for secondary growth. Which are correct?
A. 1, 2 and 3
B. 1 and 3 only
C. 2 and 3 only
D. 1 and 2 only
Answer: Option A
Solution (By JKSSB Mock Tests)
Xylem is the vascular tissue responsible for the unidirectional upward transport of water and dissolved minerals from the roots to the aerial parts of the plant. Phloem is the vascular tissue responsible for the translocation of organic nutrients (primarily sucrose) from sources to sinks, which can be bidirectional (up or down depending on the plant's needs). Cambium (vascular and cork) is a lateral meristem responsible for secondary growth, which is the increase in the girth or thickness of stems and roots. All statements are correct.
Explanation:
Pellagra, characterized by dermatitis, diarrhea, and dementia (3 Ds), is due to deficiency of niacin (vitamin B₃) or its precursor tryptophan. Niacin is part of NAD and NADP coenzymes.
Explanation:
Apoptosis is a highly regulated and organized process of programmed cell death that occurs in multicellular organisms. It is crucial for development, maintaining tissue homeostasis, and eliminating damaged or infected cells. Unlike necrosis (accidental cell death), apoptosis does not cause inflammation and involves cell shrinkage and fragmentation.
Explanation:
Cellulase hydrolyzes cellulose into glucose. It is produced by certain bacteria, fungi, and protozoa, enabling them to digest plant material. Herbivores harbor these microbes in their gut. Humans lack cellulase.
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