Biology B2-B3

notes on units two and three

HideShow resource information

Cells

Animal and Plant Cells

animal: nucleus- controls activities of cell, cytoplasm- most of the chemical reactions needed for life, cell membrane- controls passage of substances in cell, mitochondria- site of respiration, ribosomes- protein synthesis

plant: nucleus, cytoplasm, cell membranemitochondria, ribosomes, cell wall- strengthens cell and gives its shape, chloroplasts- absorb light for phs and gives colour, vacuole- keeps cell rigid

ENZYMES CONTROL ALL CHEMICAL REACTIONS IN CELLS

1 of 5

Specialised Cells

Fat Cell: Very little cytoplasm. Very few mitochondria. Expands up to 100 times its                   size

Cone Cell: Outer segment- visual pigment, changes chemically in coloured light.                       Middle segment- many mitochondria, the changes produce energy. 

Root Hair Cell: Increase surface area for water, Vacuole- affects water movement                           from soil to cell.

Sperm Cell: Long tails. Many mitochondria. Acrosome stores digestive enzymes.    Large nucleus containing half genetic info.

CELLS MAY BE SPECIALISED TO CARRY OUT A PARTICULAR FUNCTION

2 of 5

Diffusion


Rates of Diffusion: The bigger the difference in concentration, the faster the rate of diffusion

Diffusion in Living Organisms: -RESPIRATION- oxygen passes from air to lungs to cells by diffusion -SIMPLE SUGARS- glucose amino acids etc also pass through cell membranes to your gut by diffusion.

DIFFUSION IS THE NET MOVEMENT OF PARTICLES FROM AN AREA OF HIGH CONCENTRATION TO AN AREA OF LOW CONCENTRATION ALONG A CONCENTRATION GRADIENT

3 of 5

Osmosis

Animals: RED BLOOD CELLS- shrivel- if the concentration of the solution around the cell is higher than inside the cell, water will leave the cell by osmosis, making it shrivel, disabling the transportation of oxygen around the body. burst- if the concentration around the cell is lower than inside the cell, water will move into the cell, causing it to eventually burst.

Plants: Water moves into the plant by osmosis, making the cytoplasm swell and press against the cell walls. This causes pressure to build up so that no more water can ghet into the plant, making the cell hard and rigid.

OSMOSIS IS THE NET MOVEMENT OR WATER PARTICLES FROM AN AREA OF HIGH CONCENTRATION TO AN AREA OF LOW CONCENTRATION ALONG A CONCENTRATION GRADIENT

4 of 5

Active Transport

Plants AND Animal: when these cells need to move substances (such as glucose) against a concentration gradient, active transport is used.

THE MOVEMENT OF SUBSTANCES AGAINST A CONCENTRATION GRADIENT AND/OR ACROSS A CELL MEMBRANE, USING UP ENERGY.

5 of 5

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »