Cambridge IGCSE Biology

3- movement in and out of cells

Biology

Cambridge IGCSE Biology

3.1 diffusion

Diffusion is the net movement of particles from a region of their higherconcentration to a region of their lowerconcentration down a concentration gradient, as a result of their random movement

Extended energy for diffusion comes from the kinetic energy of random movement ofmolecules and ions

3.1 diffusion Diffusion importance living organisms obtain most of their requirements and riding wastes by diffusion

1- photosynthesis get CO2 by diffusion2- photo synthesis ride producing O2 as waste by diffusion 3- diffusion is important in gas exchange in respiration4- absorb digested food by diffusion 5- insect pollinated flower attract insect by diffusion

3.1 diffusion Extended Investigate the factors that influence diffusion, limited to 1-surface area,2-temperature,3-concentration gradients 4-distance

State that water diffuses through( semi permeable membranes) by osmosis

3.2 Osmosis

Investigate and describe the effects on planttissues of immersing them in solutions ofdifferent concentrations

Osmosis and plant cells

State that plants are supported by the pressureof water inside the cells pressing outwards onthe cell wall

3.2 Osmosis

osmosis is the net movement of water molecules from a region of higher water potential (dilute solution) to a region of Lower water potential (concentrated solution), through a semi permeable membrane

3.2 osmosis Extended

In hypotonic solutionOsmosis take place . Water diffuse into cytoplasm through the semi permeable membrane Cell become TURGID and TURGOR PRESSURE become high so the cell will be supported

Extended

3.2 osmosis

Plant cell will not bursts ( be destroyed ) Because the cell wall can protect it

waterpressure acting against an inelastic cell wall

In hypertonic solutionOsmosis take place . Water diffuse out of cytoplasm through the semi permeable membrane First cell SHRINKS slightly till become FLUCCIDE Then the cell membrane pulls away from the cell wall The cell is PLASMOLYSED

Extended

3.2 osmosis

3.2 Osmosis

importance of water potential andosmosis in the uptake of water by plants

Root hair take in water by osmosis which depends on the water potential in the soil So increasing amount of water in the soil leads to high water potential helps water to move into the root hair and vice versa

3.2 Osmosis and animal cells Animal cell in hypotonic solutionCytoplasm is more concentrated than solution so by osmosis water diffuse into the cellAs more and more water inter the cell then the cell membrane start to stretch Eventually the strain is too much and the cell bursts ( destroyed )

Osmosis and animal cells

3.2 Osmosis and animal cells Animal cell in hypertonic solutionCytoplasm is less concentrated than solution so by osmosis water diffuse out of the cellAs more and more water exit the cell then the cytoplasm shrinks and cell shrivels up

3.3 Active transport active transport is the movement of particles through a cell membrane

froma region of lower concentration to a regionof higher concentration using energy from respiration

What is active transport?

3.3 Active transport ExtendedExamples of active transport 1- Root hair cell Take in nitrates ions from soil while root hair cell has high concentration of nitrates comparing with those in the soil by ACTIVE TRANSPORT

Root hair cell has special transport protein which pick up nitrate ions from outside the cell Then change the shape to push nitrate into the cytoplasm by using energy from respiration

How does the kidney work?

3.3 Active transport ExtendedExamples of active transport 2- small intestine Take in glucose from the lumen of intestine into cells of villi

3- Kidney tubules