Root hairs are modifications of which type of cells?
A. Endodermal cells
B. Epidermal cells
C. Pericycle cells
D. Cortical cells
Answer: Option B
Solution (By JKSSB Mock Tests)
Root hairs are tubular extensions of epidermal cells in the zone of maturation of roots. They increase surface area for absorption of water and minerals. Cortical cells form the ground tissue, endodermis is the innermost layer of cortex with Casparian strip, and pericycle gives rise to lateral roots. Root hairs are unicellular in angiosperms, living for a short period and constantly replaced.
Explanation:
A peptide bond is a covalent bond formed between the carboxyl group (-COOH) of one amino acid and the amino group (-NH₂) of another, releasing a water molecule (condensation reaction). Glycosidic bonds link monosaccharides, phosphodiester bonds link nucleotides in DNA/RNA, hydrogen bonds stabilize secondary structures. Peptide bonds create the polypeptide backbone.
Explanation:
The sinoatrial (SA) node, located in the right atrium, generates electrical impulses spontaneously and initiates each heartbeat, setting the rhythm. It is called the natural pacemaker. The atrioventricular (AV) node delays the impulse before it travels to the ventricles. The bundle of His and Purkinje fibers conduct the impulse through the ventricles.
Explanation:
Musca domestica is the common housefly, a dipteran insect. Periplaneta americana is the American cockroach, Drosophila melanogaster is the fruit fly used in genetics, Apis indica is the Indian honeybee. Housefly can act as a mechanical vector for diseases like typhoid, cholera. Scientific names help precise identification.
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