Which cell junction in plant cells allows for cytoplasmic continuity between adjacent cells?
A. Plasmodesmata
B. Desmosomes
C. Tight junctions
D. Gap junctions
Answer: Option A
Solution (By JKSSB Mock Tests)
Plasmodesmata are microscopic channels that traverse the cell walls of plant cells, enabling the transport of water, ions, molecules, and even some viruses between them, thus ensuring cytoplasmic continuity. Gap junctions perform a similar function in animal cells, while tight junctions and desmosomes are for sealing and adhesion, respectively.
Explanation:
Relaxin is a peptide hormone produced by the corpus luteum and the placenta during pregnancy. Its primary roles are to relax the smooth muscles of the uterus (inhibiting contractions to maintain pregnancy) and to soften and increase the flexibility of the connective tissues in the pelvis, specifically the pelvic ligaments and the pubic symphysis. This relaxation and widening of the pelvic joints facilitate the passage of the baby through the birth canal during delivery.
Explanation:
Gross Primary Productivity (GPP) is the total rate of photosynthesis, or the total amount of organic matter (biomass) produced by producers (plants) per unit area per unit time, including the organic matter used in respiration. Net Primary Productivity (NPP) is GPP minus the energy used by the plants for respiration (NPP = GPP - R).
Explanation:
Urine specific gravity, a measure of solute concentration, normally ranges from 1.015 to 1.030. It varies with hydration status: low when dilute (after drinking), high when concentrated (dehydration). Diabetes insipidus shows low SG, diabetes mellitus may show high due to glucose.
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