Which blood vessels have valves to prevent backflow?
A. Capillaries
B. Arteries
C. Arterioles
D. Veins
Answer: Option D
Solution (By JKSSB Mock Tests)
Veins carry blood back to the heart under low pressure and have one-way valves that prevent backflow. Skeletal muscle contractions also assist venous return.
Explanation:
The Fluid Mosaic Model of the plasma membrane was proposed by S. Jonathan Singer and Garth Nicolson in 1972. It describes the cell membrane as a dynamic, fluid structure composed of a phospholipid bilayer with globular proteins embedded or attached, moving laterally within the lipid matrix.
Consider the following statements about mitosis:
1. It produces diploid cells.
2. It is involved in growth and repair.
3. It reduces chromosome number by half.
Which of the above is/are correct?
Explanation:
Photosynthesis converts CO₂ and water into glucose using light energy, fixing carbon. Respiration releases CO₂, combustion burns organic matter, decomposition breaks down dead matter. Photosynthesis is the main route of carbon entry into the biosphere.
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