B2a - Cells Flashcards
Similarities and differences in plant and animal cells
Sim - Nucleus, cytoplasm, cell membrane, mitochondria and ribosomes
Diff - cell wall, vacuole, chloroplast
What do mitochondria do?
this is where most of the reactions for respiration take place (respiration realises energy so cells can work)
What do ribosomes do?
Where protien-synthesis takes place - where proteins are made
What does the nucleus, cell membrane and cytoplasm do?
Nucleus - contains genetic material and controls the activities of the cell.
Cytoplasm - where most of the chemical reactions take place and contains enzymes to control these chemical reactions
Cell Membrane - to let substances in and out of the cell and hold cell together
Job of cell wall, vacuole and chloroplasts
Cell wall - supports and strengthens the cell
Vacuole - contains cell sap- a weak solution of sugar and salts.
Chloroplast - when photosynthesis takes place to make food for plant - green substance - makes leaves green
What is in a yeast cell?
Plus what is it?
Single-celled organism
nucleus, cytoplasm, cell membrane and cell wall.
What is in a bacteria cell?
Plus what is it?
Single-celled organism
Genetic material that floats in cytoplasm, cytoplasm, cell membrane and cell wall.
What is diffusion?
Is the spreading of particles from an area of high concentration to an area of low concentration.
How does a cell membrane diffuse molecules?
cell membrane lets stuff in and out
- Only very small molecules can fit through like oxygen, amino acids, glucose and water
- Bigger molecules dont fit through so can’t enter the cell - starch and proteins.
- Flow from areas of high concentration to low concentration and they will travel in and out of the cell depending on this.
How are palisade leaf cells adapted for photosynthesis?
Groped together at the top of the leaf
- Packed with chloroplasts for photosynthesis and theres more on top of the cell so they are closer to light.
- Tall shape with lots of surface area exposed for absorbing CO2 from the air in the leaf.
- Thin shape so that you can pack a lot into 1 leaf.
How are guard cells adapted to open and close pores?
allow gas exchange and control water loss
- Special kidney shape which open and closes the stomata (pores) in the leaf.
- When plant has lots of water the guard cells fill with it and go plump - making stomata’s open and gases can exchange for photosynthesis.
- When short of water guard cells loose water making stomata’s close - to stop water vapour escaping.
- Thin outer walls and thick inner walls make opening and closing work.
- Sensitive to light and close at night to save water without loosing out on photosynthesis.
How are red blood cells adapted to carry oxygen?
- Concave shape gives a big surface area for absorbing oxygen and helps them pass smoothly through capillaries to reach body cells.
- Packed with haemoglobin - pigment that absorbs oxygen
- No nucleus to leave more room for haemoglobin
How are sperm and egg cells adapted for reproduction?
Egg - Carry female DNA
Nourish the developing embryo in early stages
Contains huge food reserves to feed embryo
When sperm fertilises the eggs membrane instantly changes to no other sperm get in.
Sperm - Used to get male DNA to female DNA
Long tail and streamline head to help it swim to the egg
Lots of mitochondria to provide sperm with lots of energy to swim
Enzymes in head to digest through egg membrane
What do a group of organ systems make?
Large Multicellular organisms
What is a tissue?
A group of cells working together to carry out a particular function.
