Cells

Question 1

What is a prokaryotic cell?

Answer 1

Smaller and simpler - no nucleus

Question 2

What is a eukaryotic cell?

Answer 2

Complex - contains a nucleus

Question 3

4 features of a bacteria cell?

Answer 3

1. Cell membrane
2. Cytoplasm
3. Cell wall
4. Plasmid rings containing DNA

Question 4

2 advantages of an electron microscope

Answer 4

1. Higher resolution
2. Higher magnification

Question 5

2 disadvantages of an electron microscope?

Answer 5

1. Expensive
2. Large - not portable

Question 6

Equation for magnification?

Answer 6

magnification = image/ real

Question 7

2 ways sperm cells are specialised?

Answer 7

1. Streamlined head to swim quickly
2. Enzymes on its acrosome to fertilise egg

Question 8

2 ways nerve cells are specialised?

Answer 8

1. Long - cover distance
2. Branched - connect to other nerve cells

Question 9

2 ways muscle cells are specialised?

Answer 9

1/ Long - space to contract
2. Lots of mitochondria - energy for contraction

Question 10

2 ways root hair cells are specialised?

Answer 10

1. Long hairs - bigger surface area for absorbing water and mineral ions

Question 11

2 ways xylem and phloem are specialised?

Answer 11

1. Hollow and few subcellular structures - substances can travel through them
2. strengthened with lignin - strength

Question 12

Explain the life cycle of a cell

Answer 12

1. Cell grows more subcellular organelles
2. DNA duplicates to form x shaped chromosomes
3. Chromosomes line up down the centre and the two arms of each chromosome are pulled to either end
4. Nucleus divides and a membrane forms around the chromosomes
5. Cell cleaves and two new daughter cells are created

Question 13

Explain binary fission

Answer 13

1. Plasmids and circular DNA replicate
2. Cell expands and circular DNA move to either end of cell
3. Cytoplasm divides and new cell walls form
4. Cytoplasm divides fully - each new cell ahs one copy of circular DNA but various plasmids

Question 14

What is therapeutic cloning?

Answer 14

An embryo is made to have the same genetic information as a patient

Question 15

Risk of using stem cells

Answer 15

Stem cells grown in a lab could become contaminated with a virus which could be passed onto a patient

Question 16

2 ethical reasons against embryonic stem cells

Answer 16

1. Embryos can’t consent
2. Killing potential human life

Question 17

2 disadvantages of adult stem cells?

Answer 17

1. Can only differentiate into certain cells
2. Painful for patient

Question 18

Where are the stem cells in a plant?

Answer 18

Meristem

Question 19

How can stem cells be used to preserve rare plant life

Answer 19

Stem cells can produce clones of whole plants cheaply and quickly

Question 20

2 things that increase diffusion rate?

Answer 20

1. Bigger concentration gradient
2. Higher temperature

Question 21

What is osmosis?

Answer 21

The movement of water molecules from a region of higher water concentration to a region of lower water concentration across a partially permeable membrane

Question 22

How do root hair cells use active transport

Answer 22

When there is more mineral ions in the cell than in the soil, mineral ions move against the concentration gradient into the cell

Question 23

How is active transport used in the gut?

Answer 23

When there is a lower concentration of nutrients in the gut than the blood, active transport allows nutrients to be taken into the blood

Question 24

4 ways exchange surfaces are adapted?

Answer 24

1. Thin membrane - short diffusion pathway
2. Large surface area - more space for diffusion
3. Lots of blood vessels - easy bloodstream access
4. Ventilated - air can move in and out

Question 25

4 ways alveoli and villi are adapted for diffusion?

Answer 25

1. Huge surface area 2. Moist lining for dissolving gases 3. Very thin walls 4. Good blood supply

Question 26

Job of the stomata?

Answer 26

Letting carbon dioxide diffuse in and let water vapour and oxygen diffuse out

Question 27

Job of guard cells?

Answer 27

Open and close stomata if water is being lost faster than it is being replaced

Question 28

How do gills help fish breathe?

Answer 28

Oxygen enters into the fish through the mouth, and passes out at the gills, whilst oxygen diffuses from water to the blood and carbon dioxide diffuses from the blood to the water

Question 29

3 ways gills are adapted for gas exchange?

Answer 29

1. lamellae increase surface area 2. lots of blood capillaries 3. thin