The scientist who first observed the nucleus in plant cells was:
A. Matthias Schleiden
B. Robert Brown
C. Robert Hooke
D. Antonie van Leeuwenhoek
Answer: Option B
Solution (By JKSSB Mock Tests)
Robert Brown, a Scottish botanist, discovered the nucleus in 1831 while studying orchid cells under a microscope. He named it 'nucleus'. Hooke discovered cells, Leeuwenhoek observed living cells, Schleiden proposed that all plants are made of cells. Brown's discovery was crucial for understanding cell structure and function.
Explanation:
Fungal cell walls contain chitin, a strong, flexible polysaccharide also found in arthropod exoskeletons. Cellulose is in plant walls, peptidoglycan in bacterial walls, lignin in secondary plant walls. Chitin provides structural support and protection against environmental stress.
Explanation:
The adult vertebral column consists of 33 vertebrae (though some are fused: 5 sacral and 4 coccygeal). The femur (thigh bone) is the longest and strongest bone. The skull is composed of 22 bones (cranium and facial bones), some fused but the mandible is movable. The rib cage has 12 pairs of ribs. The stapes in the ear is the smallest bone.
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