The molecule that is the final electron acceptor in the mitochondrial electron transport chain is: MCQ with Answer and Explanation

The molecule that is the final electron acceptor in the mitochondrial electron transport chain is:
A. FAD
B. NAD⁺
C. Cytochrome c
D. Oxygen
Answer: Option D
Solution (By JKSSB Mock Tests)
Molecular oxygen (O₂) accepts electrons at the end of the electron transport chain, combining with protons to form water (metabolic water). Without oxygen, the chain backs up, stopping ATP production. This is why oxygen is vital for aerobic respiration. NAD⁺ and FAD are electron carriers, cytochrome c a component.

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Practice More Biology Questions

Question #1
In plant anatomy, the 'Periderm' is a secondary protective tissue that replaces the epidermis in stems and roots undergoing secondary growth. It consists of three main layers: the phellem, phellogen, and phelloderm. The 'phellem' is also known as:
A. Cork
B. Vascular cambium
C. Secondary cortex
D. Cork cambium

Correct Answer: Option A


Explanation:
The periderm is the outer protective covering of stems and roots that have undergone secondary growth (thickening), replacing the primary epidermis. It is composed of three distinct layers: 1) Phellem (cork): The outermost layer, consisting of dead, compactly arranged cells with suberized (waterproof) walls that provide protection and prevent water loss. 2) Phellogen (cork cambium): The middle, meristematic layer that produces phellem outwards and phelloderm inwards. 3) Phelloderm (secondary cortex): The innermost layer, consisting of living, parenchymatous cells.

This question belongs to: Science Biology
Question #2
Which of the following is a respiratory disease caused by a coronavirus?
A. Tuberculosis
B. Pneumonia caused by Streptococcus
C. Influenza
D. COVID-19

Correct Answer: Option D


Explanation:
COVID-19 is caused by SARS-CoV-2, a novel coronavirus. Tuberculosis is bacterial (Mycobacterium). Influenza is caused by influenza viruses (Orthomyxoviridae), not coronavirus. Pneumonia can be bacterial or viral, but the question specifies Streptococcus which is bacterial. COVID-19 emerged in 2019, causing a global pandemic, primarily affecting the respiratory system.

This question belongs to: Science Biology
Question #3
The organ that filters blood, removes old RBCs, and stores platelets is the:
A. Spleen
B. Liver
C. Kidney
D. Pancreas

Correct Answer: Option A


Explanation:
The spleen, located in the upper left abdomen, filters blood, removes senescent or damaged red blood cells, stores platelets and white blood cells, and mounts immune responses. The liver processes nutrients and toxins, kidneys filter blood to produce urine, pancreas secretes enzymes/hormones.

This question belongs to: Science Biology