The first stable product of CO₂ fixation in C4 plants is:
A. Oxaloacetic acid (OAA)
B. 3-phosphoglyceric acid (PGA)
C. Ribulose bisphosphate (RuBP)
D. Phosphoenolpyruvate (PEP)
Answer: Option A
Solution (By JKExamLibrary)
In C4 plants like maize and sugarcane, CO₂ is initially fixed in mesophyll cells by PEP carboxylase, producing a four-carbon compound oxaloacetic acid (OAA), which is then converted to malate or aspartate and transported to bundle sheath cells. Here, CO₂ is released and enters the Calvin cycle. This adaptation minimizes photorespiration.
Explanation:
Amoeba, a protozoan, moves and captures food using temporary, foot-like extensions of its cytoplasm called pseudopodia (false feet). This type of movement is called amoeboid movement and is driven by the assembly and disassembly of microfilaments (actin) in the cytoskeleton. Cilia and flagella are hair-like structures used by other protozoans like Paramecium and Euglena.
Explanation:
Alveoli are thin-walled air sacs where O₂ and CO₂ exchange occurs. The voice box is the larynx; diaphragm is skeletal muscle; pulmonary veins carry oxygenated blood.
Explanation:
Bacillus is a genus of rod-shaped bacteria, placed in Kingdom Monera because they are prokaryotic. Euglena and Paramecium are unicellular eukaryotes in Kingdom Protista. Agaricus (mushroom) belongs to Kingdom Fungi. Monera includes all prokaryotes like bacteria, cyanobacteria, and archaea. They are characterized by absence of true nucleus and membrane-bound organelles.
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