Bio A: Cells and organelles

Question 1

Eukaryotes and prokaryotes

Answer 1

Eukaryotes genetic material is enclosed in a nucleus eg. plants, animals.

Prokaryotes are much smaller, with their cell membrane surrounded by a cell wall, and their genetic material is not enclosed in a nucleus eg. bacteria

Question 2

Mitosis cell division

Answer 2

DNA in chromosomes copy itself for mitosis.
DNA condenses to become more visible and membrane around the nucleus disappears.
Chromosome and its copies line up in middle of the cell.
Chromosome and its copies get pulled to each end of the cell.
Membranes form around the ends of the cell.
Cell Membrane and Cytoplasm divide.
Two identical daughter cells formed.

Question 3

Purpose of mitosis

Answer 3

Growth and repair from asexual reproduction.

Question 4

Cell cycle

Answer 4

Replication of DNA and organelles
Nucleus divides by mitosis
Cell division

Question 5

Differentiation

Answer 5

The process which cells, tissues and organs obtain specialised features to carry out functions.

Question 6

What is a stem cell?

Answer 6

An undifferentiated cell found in animals and plants

Question 7

Embryonic stem cells

Answer 7

Divide into larger amounts and can grow into any cell in the body.

Question 8

Adult stem cells

Answer 8

Divide into smaller amounts and replace body cells that die through injury and disease.

Question 9

Ethical considerations - stem cells

Answer 9

Viral infections could her transferred.

Destroying a potential human life.

Question 10

Aerobic respiration

Answer 10

The breaking down of food substances using oxygen to release energy in cells.
Glucose + oxygen —-> Carbon Dioxide + water

Question 11

Anaerobic respiration

Answer 11

The breaking down of food substances without oxygen to release energy in cells.

Question 12

Anaerobic respiration in muscles

Answer 12

Glucose –> lactic acid
Glucose not completely broken down so less energy released.
Build up of lactic acid in muscles needs to be oxidised to CO2 and H2O later.

This causes an oxygen debt which needs to be repaid after exercise has stopped eg. heavy breathing

Question 13

Anaerobic respiration in plants and yeast

Answer 13

Glucose –> Ethanol + Carbon Dioxide

In bread, bubbles of CO2 gas expand and help the dough to rise giving it a fluffy texture.
Ethanol is evaporated away.

Question 14

Sperm cell specialisation

Answer 14

Mitochondria to release energy allowing the sperm to swim.

Tail enables the sperm to swim efficiently towards to the egg

Question 15

Nerve cell specialisation

Answer 15

The cell has dendrites so it can communicate with other nerve cells, muscles and glands.
Myelin sheath insulates nerve cell and speeds up impulses.

Question 16

Muscle cell specialisation

Answer 16

Filaments of protein slide over each other to cause muscle contraction.
Mitochondria provides energy for muscle contraction.

Question 17

Root hair cell specialisation

Answer 17

Root hair cell has a large surface area for absorption of water.
Thin walls to not restrict movement of water

Question 18

Ciliated cell specialisation

Answer 18

Thin layers of hair called a ‘cilia’ which moves mucus from one place to another
Mitochondria to help with mucus movement