In the C4 photosynthetic pathway, the primary CO2 acceptor is: MCQ with Answer and Explanation

In the C4 photosynthetic pathway, the primary CO2 acceptor is:
A. Oxaloacetate (OAA)
B. Phosphoenolpyruvate (PEP)
C. Ribulose-1,5-bisphosphate (RuBP)
D. Malate
Answer: Option B
Solution (By JKSSB Mock Tests)
In C4 plants, the initial fixation of CO2 occurs in the mesophyll cells. The primary CO2 acceptor is a 3-carbon compound, phosphoenolpyruvate (PEP). The enzyme PEP carboxylase catalyzes the reaction, forming a 4-carbon compound, oxaloacetate (OAA). In C3 plants, the primary acceptor is RuBP, a 5-carbon compound, and the enzyme is RuBisCO.

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Question #1
Which part of the brain regulates body temperature, hunger, and thirst?
A. Hypothalamus
B. Pons
C. Cerebellum
D. Medulla oblongata

Correct Answer: Option A


Explanation:
The hypothalamus is a small region in the forebrain that maintains homeostasis by regulating body temperature, hunger, thirst, sleep, and emotions. It also controls pituitary gland secretions. The cerebellum coordinates movement, medulla controls respiration and heart rate, pons relays signals. Hypothalamus acts as the body's thermostat and the link between nervous and endocrine systems.

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Question #2
Which of the following is the correct sequence of taxonomic hierarchy from lowest to highest?
A. Species → Genus → Order → Family → Class → Phylum → Kingdom
B. Species → Family → Genus → Order → Class → Phylum → Kingdom
C. Species → Genus → Family → Order → Class → Phylum → Kingdom
D. Genus → Species → Family → Order → Class → Phylum → Kingdom

Correct Answer: Option C


Explanation:
The correct taxonomic hierarchy in ascending order is: Species (lowest) → Genus → Family → Order → Class → Phylum (or Division in plants) → Kingdom (highest). Some classifications add Domain above Kingdom. This system groups organisms based on shared characteristics. Binomial nomenclature uses Genus and Species. Option A correctly places Family before Order.

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Question #3
The molecule that carries the genetic information from DNA to the ribosome is:
A. snRNA
B. mRNA
C. rRNA
D. tRNA

Correct Answer: Option B


Explanation:
Messenger RNA (mRNA) is transcribed from DNA and carries the codon sequence to ribosomes, where it is translated into a polypeptide. tRNA brings amino acids, rRNA forms ribosomal structure, snRNA involved in splicing.

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