Biology Chapter 3 Cellular Organisation

The correct answer is differentially permeable. This term refers to the property of the cell membrane that allows certain substances to pass through while restricting the passage of others. The cell membrane is selectively permeable, meaning it regulates the movement of molecules and ions in and out of the cell. It controls the exchange of essential nutrients and waste products, maintaining the internal environment of the cell. This characteristic is crucial for cellular function and homeostasis.

When we put a layer of onion epidermis under the light microscope, we can see the cell wall. The cell wall is a rigid structure that surrounds the cell membrane and provides support and protection to the cell. It is made up of cellulose and can be easily observed under a light microscope as a clear, outer layer surrounding the cell.

Organelles are the structures in the cytoplasm. Cell wall is not in the cytoplasm.

Lipids are produced in the smooth endoplasmic reticulum (SER) of a cell. The SER is responsible for the synthesis of lipids, including phospholipids, steroids, and triglycerides. It does not have ribosomes attached to its surface, unlike the rough endoplasmic reticulum (RER). The RER is involved in protein synthesis. The mitochondrion is responsible for energy production in the form of ATP, and the nucleolus is involved in the production of ribosomes. Therefore, the correct answer is the smooth endoplasmic reticulum.

The total magnification of a light microscope is calculated by multiplying the magnification of the objective lens with the magnification of the eyepiece. In this case, the total magnification is given as 400X and the magnification of the objective lens is 10X. To find the magnification of the eyepiece, we divide the total magnification by the magnification of the objective lens. Therefore, the magnification of the eyepiece is 400X / 10X = 40X.

Vacuole only has a single membrane, not double.

Animal cells may have no vacuole or small vacuoles.
Not all plant cells have chloroplasts.
Plant cells also have mitochondria. They require energy for growth and repair etc.

To adjust the brightness of the image under a light microscope, you should adjust the iris diaphragm. The iris diaphragm is a part of the microscope that controls the amount of light passing through the specimen. By adjusting the iris diaphragm, you can increase or decrease the amount of light entering the microscope, thereby making the image brighter or dimmer.

The statement "The image under light microscope has higher resolution than that under electron microscope" is not a correct description because electron microscopes have much higher resolution than light microscopes. Electron microscopes use a beam of electrons instead of light, allowing them to achieve much higher magnification and resolution.

Red blood cells do not have mitochondria.
Although bacteria can carry out respiration, they do not have mitochondria. They have infolding membrane to perform the respiration.
Fat cells are not active. They do not need many mitochondria.
Sperms require many mitochondria to provide a lot of energy for swimming.