Which pair of features is correct for both diffusion and osmosis?
▶️Answer/Explanation
Answer: D
Explanation:
First, quick definitions:
- Diffusion = Net movement of particles (like gases) from high to low concentration, passively (no energy).
- Osmosis = A type of diffusion, but specifically for water across a partially permeable membrane, also passive.
Let’s check each option:
A. Incorrect – Diffusion is correctly described as movement from high to low concentration, but osmosis is incorrectly labeled as active transport. Osmosis is a passive process.
B. Incorrect – Diffusion is wrongly described as low to high concentration, which actually defines active transport. Osmosis is also wrongly labeled as active transport.
C. Incorrect – Diffusion is again wrongly described as movement from low to high concentration. Osmosis is correctly described as a passive process, but since diffusion is wrong, the whole pair is incorrect.
D. Correct – Diffusion is correctly described as passive movement from high to low concentration. Osmosis is also correctly described as passive movement of water across a partially permeable membrane. Both definitions are accurate.
How do mineral ions in the soil move into the root?
A. Osmosis
B. Mass flow of water
C. Translocation
D. Through phloem
Answer/Explanation
Answer: B. Mass flow of water
Explanation:
- Mineral ions (like nitrate, phosphate, potassium) in the soil are typically dissolved in water.
- When plants absorb water from the soil through root hairs, these dissolved mineral ions are also taken up.
- This movement is mainly driven by the mass flow of water towards the root, especially due to transpiration pull and water potential differences.
Why not the others?
A. Osmosis → This is for water movement, not ions.
C. Translocation → Happens in phloem, moves sugars, not minerals from soil.
D. Through phloem → Wrong tissue! Minerals move into the root via xylem, not phloem.
So, once minerals enter the root, they move up the plant via the xylem, not phloem
Which process and cause are responsible for water uptake by the roots?
Answer/Explanation
Answer: B
Explanation:
- Water uptake by roots happens by osmosis.
- Osmosis is the movement of water from an area of lower solute concentration (i.e. the soil) to higher solute concentration (inside root cells) through a partially permeable membrane.
- So, for water to move into the root:
- The solute concentration must be greater in the root than in the surrounding soil.
- This creates a water potential gradient driving osmosis.
Why others are wrong:
A. Simple diffusion: Diffusion doesn’t involve water across membranes; and water movement is not by “simple” diffusion here.
C. Osmosis, but lower solute in root: Water would move out of the root in this case, not in.
D. Cohesion: Cohesion refers to water molecules sticking together (important for upward xylem transport), not root absorption.