Zusammenfassung der Ressource
AQA GCSE Biology B2.1
Cells and simple cell transport
- Cell and Cell Structure
- All living things made of cells. Small only seen with a microscope.
- Most human and animal cells have the following:
- A nucleus which controls the activities of the cell.
Also contains the chromosomes
- A cell membrane which that controls the
movement of substances into and out of the cell
- Cytoplasm which is where many of the
chemical reactions happen in the cell
- Mitochondria which is where respiration takes place,
where energy is released during aerobic respiration
- Ribosomes where protein synthesis takes place
- In addition to these things plant and algal cells also have:
- A rigid cell wall made of cellulose to
help keep the structure of the cell & strengthens it
- A permanent vacuole filled with cell sap
- Chloroplasts which contain chlorophyll
which is a green substance that
absorbs sunlight for photosythesis
- Plant cells are different from
animal cells because they have
different functions
- Bacteria & Yeast
- Bacteria are v small
- Bacterial cells have a cell membrane and cytoplasm surrounded by a cell wall
- Bacterial cells do not have a nucleus so the genetic material is in the cytoplasm
- Yeast is a single celled organism
- Yeast cells have a nucleus, cytoplasm and a
membrane surrounded by a cell wall
- Specialised Cells
- Cells may be specialised to carry out a particular function
- For example:
- Sperm cells have a tail so that they
can swim and a rounded head so
that they are streamlined to aid
swimming
- Root Hair cells
are long and thin
to absorb water
and nutrients
from the cell
- Muscles cells have many
mitochondria as they
need a lot of energy
- The structure of
a cell gives a clue
to its function
- Diffusion
- Dissolved
substances can
move into and out
of cells by diffusion
- Diffusion is the spreading of particles
of gas or of any substance in solution
resulting in net movement from an area
of high concentration into an area of
low concentration
- The difference in concentration between the two
areas is called the concentration gradient ~
Diffusion happens when particles move down the
concentration gradient
- The larger the difference in concentration the faster the rate of diffusion
- The shorter the diffusion distance the quicker it occurs
- The larger the surface area for diffusion the faster it occurs
- The smaller the particles the faster the rate of diffusion
- Oxygen required for respiration passes through cell
membranes by diffusion