The part of the neuron that is usually myelinated and conducts impulses away from the cell body is the:
A. Cell body
B. Axon
C. Synapse
D. Dendrite
Answer: Option B
Solution (By JKSSB Mock Tests)
The axon is a long, slender projection of the neuron that carries nerve impulses (action potentials) away from the soma to other neurons, muscles, or glands. Axons are often insulated by a myelin sheath. Dendrites receive signals, the cell body contains the nucleus, the synapse is the junction.
Explanation:
Alveoli are tiny, thin-walled air sacs surrounded by a network of pulmonary capillaries. Oxygen diffuses from alveolar air into blood, and CO₂ diffuses from blood into alveolar air. Bronchi and bronchioles are air passages, trachea is the windpipe. The large surface area of alveoli (about 70 m²) facilitates efficient gas exchange.
Consider statements about human skeleton: 1. The human skull has 22 bones. 2. The femur is the longest bone. 3. Ribs are attached to the sternum directly or indirectly. Which are correct?
Explanation:
The human skull consists of 22 bones (8 cranial and 14 facial). The femur (thigh bone) is the longest and strongest bone in the human body. Humans have 12 pairs of ribs; the first 7 are true ribs (direct attachment), next 3 are false ribs (indirect), and last 2 are floating. All statements are anatomically correct.
Explanation:
Viruses are non-living outside a host cell and must hijack a host's cellular machinery to replicate, making them obligate intracellular parasites. They contain either DNA or RNA, not both (except some rare cases). They lack cell walls and metabolic machinery. Their status as living or non-living is debated, but they are biologically active only inside a host.
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