Question 1) Define plasmolysis.
Question 2) Why is endocytosis found in animals only?
Question 3) What is active transport? Question 4) Define plasmolysis Question 5) What is endocytosis? Question 6) Differntiate between diffusion and osmosis.
Question 7) How does an Amoeba obtain its food?
Question 8) What is membrane biogenesis? How is plasma membrane formed during this process?
Question 9) What are semiautonomous organelles? Describe with ?
Answers
Answer:
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1) Plasmolysis :
The shrinking of protoplasm away from the cell wall of a plant or bacterium due to water loss from osmosis, thereby resulting in gaps between the cell wall and cell membrane.
2) The presence of cell wall in plants cells which is a rigid covering beyond the cell membrane of plant cells. The cell wall might be the reason endocytosis is hampered in plants cells.
3) Active transport :
In cellular biology, active transport is the movement of molecules across a membrane from a region of their lower concentration to a region of their higher concentration—against the concentration gradient.
4) Plasmolysis :
Plasmolysis is when plant cells lose water after being placed in a solution that has a higher concentration of solutes than the cell does. This is known as a hypertonic solution. Water flows out of the cells and into the surrounding fluid due to osmosis. This causes the protoplasm, all the material on the inside of the cell, to shrink away from the cell wall.
5) Endocytosis :
Endocytosis is a cellular process in which substances are brought into the cell. The material to be internalized is surrounded by an area of plasma membrane, which then buds off inside the cell to form a vesicle containing the ingested material. Endocytosis includes pinocytosis (cell drinking) and phagocytosis (cell eating). It is a form of active transport.
6) Difference between Osmosis and Diffusion
Osmosis Diffusion
It is limited only to the liquid medium. Occurs in all mediums – Solid,
Liquid and gas.
Requires a semipermeable membrane. Do not require a semipermeable membrane.
Depends on the number of solute Depends on the presence of
particles dissolved in the solvent. other particles.
Requires water for the movement Do not require water for the
of particles. movement of particles.
Only the solvent molecules can Both the molecules of solute
diffuse. and solvent can diffuse.
The flow of particles occurs only in The flow of particles occurs
one direction. in all the directions.
The entire process can either be This process can neither be
stopped or reversed by applying stopped nor reversed.
additional pressure on the solution
side.
7) Amoeba obtains its food by the process of endocytosis. ... It engulfs the food particle with the help of pseudopodia and then forms a vacuole around it. When the particle is completely trapped the amoeba secretes digestive enzymes that digests the food. thus the amoeba obtains it's food.
8) Membrane biogenesis is a process which is carried out by the two endoplasmic reticulum’s in which the they synthesise lipids and proteins which are the two components from which a plasma membrane is made up of. So once the lipids and proteins have been synthesised and further made complex by golgi apparatus it travels in the form of a vacuole near the plasma membrane where the vacuole deposits the lipids and proteins because of which the plasma membrane is formed.
Membranes synthesised by this process of membrane biogenesis help in dividing the cell into structural and functional compartments. Membranes of the cell altogether are called as endomembrane system. The endomembrane system includes different membranes suspended in the cytoplasm and the plasma membrane.