cells

Question 1

1. draw and label an animal cell
2. what is the function of each organelle
3. draw and label a plant cell
4. what is the function of each organelle
5. what are the differences between a plant and animal cell

Answer 1

1. nucleus: controls the cell and stores DNA
   cytoplasm: chemical reaction
   cell membrane: controls what goes in and out
   mitochondria: respiration
   ribosomes: protein synthesis
2. cell wall: keeps the cell ridged
   vacuole: contains cell sap
   chloroplast: photosynthasis
3. cell wall, vacuole and chloroplast

Question 2

1. draw and label a bacteria cell

2. how is it different to a plant or animal cell

Answer 2

1. plasmids: loops of dna
   chromosonal membrane: coiled lengths of dna
   cell wall: keep cell ridged
   cell membrane: controls what goes in and out
   flagellum: tail to help it swim
2. dna is in loops
   much smaller
   contains plasmids
   no nucleus

Question 3

1. how is a sperm cell specialised for its function
2. how is a nerve cell specialised for its function
3. how is a muscle cell specialised for contractions
4. how are root hair cells specialised for absorbing water and minerals
5. how are the phloem and xylem adapted to transport nutrients

Answer 3

1. flagellum to swim to egg. enzymes around head to break into egg. lots of mitochondria to swim to egg.
2. long branch like connections. carries electrical signals, very long.
3. space to contract. lots of mitochondria.
4. hollow long tubes. xylem is hollow. phloem has very subcellular cell.

Question 4

1. Describe what is meant by ‘differentiation of a cell’?
2. In animal cells, when does differentiation happen?
3. In which part of a plant does differentiation of cells happen?
4. In what way is differentiation of plant cells different to differentiation of animals?

Answer 4

1. A cell becoming specialised
2. Very early in development
3. Stomata
4. Plants can happen anytime

Question 5

1. How are electron microscopes different to light microscopes?
2. What are the advantages of electron microscopes?
3. What is the equation linking image size, actual size and magnification?
4. How many micrometres (µm) are there in 1 millimetre (mm)?
5. How do you convert millimetres into micrometres?
6. How do you use a light microscope to observe, draw and label biological specimens?

Answer 5

1. can get a higher magnification
2. can see electrons and it higher resolution
3. image= mag/actual
4. 1000

Question 6

1. What are chromosomes?
2. How many chromosomes are in human cells?
3. Give two reasons why cells need to divide?
4. What do cells do before they divide?
5. Describe the 4 main steps of the cell cycle

Answer 6

1. Coiled lengths of dna
2. 46 or 23 pairs
3. Growth and repair
4. Duplicate nuclear membranes
5. Duplicate, Aline in centre of cell, split membranes, form into 2

Question 7

1. What are stem cells?
2. State two locations in humans where stem cells can be found
3. Where are stem cells found in plants?
4. Why are stem cells useful?
5. Describe a potential use for stem cells
6. Explain why some people are against using stem cells
7. Describe a use of plant stem cells

Answer 7

1. Unspecialised cells
2. embryo and bone marrow
3. meristem
4. can differentiate into any specialised cell
5. curing disease
6. potential form of life
7. cloning

Question 8

1. Define diffusion
2. State the factors that affect the rate of diffusion
3. Give two examples of where diffusion happens in the human body
4. Give one example where diffusion happens in plants
5. Describe gas exchange in fish

Answer 8

1. The movement of particles from a low to high concentration
2. Temperate, surface area, concentration gradient
3. Alveoli and small intestine
4. Gills
5. Oxygen enters through gills and leaves through mouth

Question 9

1. Define osmosis
2. What is a partially permeable membrane?
3. How do you investigate the effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue

Answer 9

1. The movement of water molecules from a high to low concentration through a partially permeable membrane
2. Membrane with gaps or holes
3. Measure 5 equal tubes of potatoes. Then measure their starting mass. Place them in the 5 tubes of solution each with a different salt or sugar concentration. Leave them for 2hr to 24 hrs. Take them out and dry them off gently with a towel. Measure their final mass. Calculate the percentage change in mass.

Question 10

1. Define active transport
2. Where does the energy for active transport come from?
3. Give an example of active transport in plants
4. Describe how a root hair cell is adapted for diffusion, osmosis and active transport
5. Give an example of active transport in humans

Answer 10

1. The movement of particles form a low to high concentration against the concentration gradient.
2. Respiration
3. Alveoli and villi
4. Large surface area, efficient blood supply and thin membranes