The Fundamental Unit of Life

Differences between plant and animal cells:

In case the plasma membrane ruptures or breaks down, the protoplasm may leak out of the cell exposing the cell components to the external environment and eventually the cell will die.

The absence of Golgi apparatus will have the following consequences for the cell:

1. It would severely impact the cell's ability to modify, sort, and transport proteins and lipids, leading to disruptions in various cellular processes ultimately leading to cell death.
2. Without Golgi apparatus, the lysosomes might not form properly, leading to cellular waste buildup and potential toxicity.

Mitochondria is known as powerhouse of the cell as it is responsible for the process of respiration releasing energy in the form of ATP.

The lipids and proteins constituting the cell membrane are synthesised by the smooth endoplasmic reticulum and rough endoplasmic reticulum respectively.

The flexibility of the cell membrane enables Amoeba to obtain its food through a process known as endocytosis. It uses pseudopodia, temporary extensions of its cell membrane, to surround and engulf its food. The engulfed particles are then enclosed in a food vacuole, where digestion takes place.

Osmosis is the movement of water molecules from their region of higher concentration (dilute solution or with a lower solute concentration) to their region of lower concentration (concentrated solution or with a higher solute concentration) through a semi permeable membrane.

(i) Potato cups B and C have sugar and salt respectively in them. The sugar and salt form a concentrated or hypertonic solution in the potato cups. This will cause osmosis to occur in which the water molecules will move from their higher concentration (outside) to their lower concentration (inside the cup) i.e., from hypotonic solution to hypertonic solution. Therefore, the level of water will increase in the potato cups B and C.

(ii) Potato A serves as a control for the experiment.

(iii) Water does not collect in cup A because cell sap and water become isotonic.

Water does not collect in cup D because the cells of potato died due to boiling. After boiling the cell membrane cannot function like a semi-permeable membrane and hence there will be no passage of water through it.

Mitosis is the cell division required for growth and repair of body.

Meiosis is the cell division involved in formation of gametes (haploid cells).

Cells were discovered by Robert Hooke in 1665. He was examining a thin slice of cork with a self-designed microscope when he saw that the cork resembled the structure of a honeycomb consisting of many little compartments. Robert Hooke called these compartments as cells.

The cell is called the structural and functional unit of life because it is smallest part of the body which forms the structure of all living things and carries out all basic life processes like respiration, nutrition, excretion independently.

The cell membrane, is selectively permeable i.e., it allows some substance to pass through it while prevents other substances from crossing.

Movement of CO₂ — CO₂ moves in and out of the cell by diffusion. It accumulates in high concentrations inside the cell. In the cell's external environment, the concentration of CO₂ is low as compared to that inside the cell. Therefore, CO₂ moves out of the cell, from a region of high concentration, to a region of low concentration by the process of diffusion.

Movement of Water — Water also moves in and out of the cell according to the concentration gradient by the process of osmosis. The movement of water across the plasma membrane is also affected by the amount of substance dissolved in water. Thus, osmosis is the net diffusion of water across a selectively permeable membrane toward a higher solute concentration.

The plasma membrane allows or permits the entry and exit of some materials in and out of the cell but also prevents movement of some other materials. Therefore, the cell membrane is called a selectively permeable membrane.

Mitochondria and Plastids are the two organelles that contain their own genetic material.

If the organisation of a cell is destroyed due to some physical or chemical influence, the cell may stop to function and finally die. A dead cell is digested by its own lysosomes.

Lysosomes contain powerful digestive enzymes capable of breaking down all organic material. During the disturbance in cellular metabolism or any damage to the cell, the lysosomes may burst and the enzymes digest their own cell. Therefore, lysosomes are known as suicide bags of a cell.

Ribosomes attached to the surface of rough endoplasmic reticulum (RER) are the sites of protein synthesis inside the cell.