Biology - Cells

What 3 parts do plant cells have that an animal cells don't, and what are their functions?

1. A Cell Wall - Made of cellulose - Strengthens the cell

2. Chloroplasts - (in most but not all plant cells) - Using chlorophyll they absorb sunlight, which is made into food

3. A Permanent Vacuole - (in most but not all plant cells) - Filled with sap which helps keep the cell rigid.

What features do ALL living cells include, and what are their functions?

1. A nucleus - Controls what the cell does and contains genetic information.

2. Cell Membrane - Controls movement in and out of the cell

3. Cytoplasm - Where most chemical reactions take place. May have mitochondria in.

4. Ribosomes - Where proteins are made (protein synthesis)

5. Mitochondria - Where most of the energy is released during respiration

What is a specialised cell?

A cell that has a structure adapted to suit the particular job it does.

Give 3 examples of specialised cells and explain how they are adapted to their job

1. Root hair cells have tiny hair like structure = large surface area for water to move into the cell. Also have a large permanent vacuole - movement of water from soil to root cell. Thirdly, always positioned close to xylem tissue - carries water to rest of plant.

2. Sperm cells have long tails to swim towards egg, Middle section full of mitochondria to provide energy, digestive enzymes in acrosome to break down layers of the egg and a large nucleus to pass on genetic information.

3. Cone Cells from Human Eyes have visual pigment in the outer section, mitochondria in the middle section to give the visual pigment energy to reform and finally a synapse connected to the optic nerve which carries nervous impulses to your brain so you can see.

What do speciallised cells that have been grouped together turn into?

Tissue, which can then turn into organs, which then can become organ systems and eventually make up your whole body

What factors speed up diffusion?

If there is a big difference in concentration between the two areas, then diffusion happens more quickly.

If the temperature is higher, the particles have more energy and move faster, therefore the rate of diffusion is increased.

What is 'net movement?'

The overall movement. You work it out by subtracting the number of particles moving out from the number of particles moving in.

What is diffusion?

The net movement of particles from an area of high concentration to an area of low concentration.

Where does diffusion happen in the body?

Diffusion happens in the cells. Many important substances can move across the membrane of the cell by diffusion, including water, amino acids and glucose.

Why do some cells have infolding cell membranes?

To make diffusion easier and more rapid, as it makes a bigger surface area.

What is osmosis?

The movement of water from a dilute solution to a concentrated solution.

What is a partially permeable membrane, and what does it do?

A partially permeable membrane is what osmosis is caused by. It lets through small water molecules through, but not larger molecules such as sugar.