Fundamental Unit Of Life. Flashcards
What is the role of the cell wall in plant cells?
Plant cells have a rigid cell wall made of cellulose that provides support, shape, and protection. Animal cells lack a cell wall.
How does the cell membrane control what enters and leaves the cell?
The cell membrane is selectively permeable, meaning it allows certain substances to pass through while blocking others. It does this through various mechanisms like:
- Passive transport: Movement of molecules across the membrane without energy input (diffusion, osmosis).
- Active transport: Movement of molecules across the membrane against a concentration gradient using energy (requires proteins in the membrane).
Why did scientist out 3 potato strips instead of one ?
1) to reduce errors in measurement .
2) to confirm results of experiment .
3) to be sure about readings .
What are prokaryotic cell ?
Cells which do not possess a well defined nucleus . They do not have membrane bound organelles . Example : blue green algae and bacteria .
What are eukaryotic cell ???
Cells which are advanced and possess a well defined nucleus . Membrane bound organelles are present . They further divide into plant and animal cells .
Characteristics of cell?
1) structural and functional unit of life .
2) size ranges from 1 to 100 micrometer .
3) can replicate independently.
4) it contains hereditary information.
5) performs all life sustaining activities by themselves.
Why is virus an exception to cell theory ?
Viruses do not have any membrane and therefore do not show characteristics of life until and unless they enter a living organism . So cell theory is not true .
Name of book written by Robert hooke ?
Micrographia .
Name the cell which is :
1) greatest length .
2) smallest .
3) largest .
1) Nerve cell .
2) Sperm .
3) Ovum .
Give a brief account of plasma membrane?
It is living , flexible , selectively permeable membrane . It is made up of phospholipids and proteins and polysaccharides . Fluid mosaic model given by Singer and Nicolson .
What is selectively permeable and permeable ?
Selectively permeable - Plasma Membrane .
Permeable - Cell wall .
If plasma membrane of cell is ruptured what will happen ?
It makes boundary of cell content . If it’s ruptured the entire cell content will be lost and cell will die .
What happens to RBC placed in hypotonic solution?
It will burst due to endosmosis.
Why does our skin of fingers shrink when we wash clothes ???
Detergent is a hypertonic solution in comparison to skin cells . When our skin comes in contact with detergent due to differences in osmotic concentration, our skins shrink due to exosmosis.
Why does a person vomit after drinking a salt solution?
Whena concentrated solution ( hypertonic solution . ) is taken in , due to exosmosis excessive dehydration of cells happens. This causes vomiting .
