The phylum that includes organisms with jointed appendages and an exoskeleton of chitin is:
A. Annelida
B. Mollusca
C. Echinodermata
D. Arthropoda
Answer: Option D
Solution (By JKExamLibrary)
Arthropoda is the largest phylum, characterized by jointed appendages, segmented body, and chitinous exoskeleton. Examples: insects, crustaceans, arachnids. Mollusca have a muscular foot and shell, Annelida have segmented worms, Echinodermata have spiny skin and radial symmetry. Arthropods have an open circulatory system.
Explanation:
Due to the rigid cell wall, plant cells form a cell plate at the equator, which develops into a new cell wall separating daughter cells. Animal cells form a cleavage furrow.
Explanation:
Ovulation is triggered by a sudden and massive surge in Luteinizing Hormone (LH) from the anterior pituitary, typically around the 14th day of a 28-day cycle. This LH surge causes the mature Graafian follicle to rupture and release the secondary oocyte. FSH stimulates follicular growth earlier in the cycle. Estrogen peaks just before the LH surge, and progesterone peaks after ovulation during the luteal phase.
Explanation:
Aspergillus niger is a fungus widely used for the industrial production of citric acid (a common food additive) through fermentation. Penicillium chrysogenum produces penicillin, Saccharomyces cerevisiae is used in baking and brewing, Rhizobium is a nitrogen-fixing bacterium. Citric acid is used as a preservative and flavor enhancer.
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