Movement by diffusion is passive, and may be from one part of the cell to the other, or from cell to cell, or over short distances, say, from the intercellular spaces of the leaf to the outside. No energy expenditure takes place. In diffusion, molecules move in a random fashion, the net result being substances moving from regions of higher concentration to regions of lower concentration. Diffusion is a slow process and is not dependent on a ‘living system’. Diffusion is obvious in gases and liquids, but diffusion in solids is more likely rather than of solids. Diffusion is very important to plants since it is the only means for gaseous movement within the plant body.

How do substances like CO 2 and water move in and out of the cell? Discuss.

The molecules, in general, tend to move from a place of their higher concentration to a lower concentration. This process is known as diffusion. The diffusion of water across a semi-permeable membrane is called osmosis. It can be observed between the cytoplasm of cells and extracellular fluid. The molecules such as CO 2 and water move across a cell with respect to their concentration gradient. If the concentration of CO 2 and water molecules is high within the cytoplasm of a cell as compared to extracellular fluid, they move outside the cell and vice versa.

The molecules, in general, tend to move from a place of their higher concentration to lower concentration. This process is known as diffusion. The diffusion of water across a semipermeable membrane is called osmosis. It can be observed between the cytoplasm of cells and extracellular fluid.

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Colourless plastids are known as (leucoplasts/chloroplasts).

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Important Questions on The Fundamental Unit of Life

EASY

Science>Biology>The Fundamental Unit of Life>Structural Organisation of a Cell

Which type of ER will be more developed in protein-synthesizing cells?

MEDIUM

Science>Biology>The Fundamental Unit of Life>Structural Organisation of a Cell

Where do the lipids and proteins constituting the cell membrane get synthesised?

EASY

Science>Biology>The Fundamental Unit of Life>Structural Organisation of a Cell

Why is the plasma membrane called a selectively permeable membrane?

MEDIUM

Science>Biology>The Fundamental Unit of Life>Structural Organisation of a Cell

What is diffusion?

MEDIUM

Science>Biology>The Fundamental Unit of Life>Structural Organisation of a Cell

Which organelle is known as the powerhouse of the cell? Why?

EASY

Science>Biology>The Fundamental Unit of Life>Structural Organisation of a Cell

Can you name the two organelles we have studied that contain their own genetic material?

MEDIUM

Science>Biology>The Fundamental Unit of Life>Structural Organisation of a Cell

Swelling of raisins in pure water proves the process of

EASY

Science>Biology>The Fundamental Unit of Life>Structural Organisation of a Cell

Why are lysosomes known as suicide bags?

MEDIUM

Science>Biology>The Fundamental Unit of Life>Structural Organisation of a Cell

What would happen to the life of a cell if there was no Golgi apparatus?

HARD

Science>Biology>The Fundamental Unit of Life>Structural Organisation of a Cell

Carry out the following osmosis experiment:
Take four peeled potato halves and scoop each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,
(a) Keep cup A empty
(b) Put one teaspoon sugar in cup B
(c) Put one teaspoon salt in cup C
(d) Put one teaspoon sugar in the boiled potato cup D.
Keep these for two hours. Then observe the four potato cups and answer the following:
(i) Explain why water gathers in the hollowed portion of B and C.
(ii) Why is potato A necessary for this experiment?
(iii) Explain why water does not gather in the hollowed-out portions of A and D.

MEDIUM

Science>Biology>The Fundamental Unit of Life>Structural Organisation of a Cell

Name the chemical substance which constitutes the genes (write the full form).

MEDIUM

Science>Biology>The Fundamental Unit of Life>Structural Organisation of a Cell

Name two types of endoplasmic reticulum present in the cells.

MEDIUM

Science>Biology>The Fundamental Unit of Life>Structural Organisation of a Cell

What would happen if the plasma membrane ruptures or breaks down?

EASY

Science>Biology>The Fundamental Unit of Life>Structural Organisation of a Cell

Organelle other than nucleus, containing DNA is