Cell Biology - Division

Question 1

Cell

Answer 1

The smallest structural and functional unit of an organism

Question 2

Nucleus

Answer 2

A structure that contains genetic material and controls the activities of the cell

Question 3

Chromosome

Answer 3

A thread like structure of coiled DNA found in the nucleus of eukaryotic cells

…and Jakub has an extra

Question 4

DNA

Answer 4

A polymer made up of two strands forming a double helix

Question 5

Gene

Answer 5

A section of DNA that codes for a specific protein or characteristic

Question 6

Cell division (mitosis)

Answer 6

Cells divide in a series of stages. The genetic material is doubled and then divided into two identical cells.

Question 7

Growth - Stage 1 of Mitosis

Answer 7

Increase the number of sub-cellular structures e.g. ribosomes and mitochondria

Question 8

DNA Synthesis - Stage 2 of Mitosis

Answer 8

DNA replicates to form two copies of each chromosome

Question 9

Mitosis - Stage 3

Answer 9

One set of chromosomes is pulled to each end of the cell and the nucleus divides. Then the cytoplasm and cell membranes divide to form two cells that are identical to the parent cell.

Question 10

When does mitosis occur?

Answer 10

Mitosis occurs during growth, repair, replacement of cells.
Asexual reproduction occurs by mitosis in both plants and simple animals.

Question 11

Undifferentiated cells of an organism

Answer 11

Divides to form more cells of the same type, and can differentiate to form many other cell types.

Question 12

Human Embryonic stem cells

Answer 12

Can be cloned and made to differentiate into most cell types.

Therapeutic cloning uses the same genes so the body does not reject the tissue. Can be a risk of infection.

Question 13

Adult bone marrow stem cells

Answer 13

Can form many types of human cells e.g. blood cells

Tissue is matched to avoid rejection, risk of infection. Only a few types of cells can be formed.

Question 14

Meristems (plants)

Answer 14

Can differentiate into any plant cell type throughout the life of the plant.

Used to produce clones quickly and economically, e.g. rare species, crop plants with pest/disease resistance

Question 15

Treatment using stem cells - why

Answer 15

Treatment with stem cells may be able to help conditions such as diabetes and paralysis. Soke people object to the use of stem cells on ethical or religious grounds (embryos in human embryonic stem cells, if you’re against abortion for some reason)

Question 16

Rule of diffusion

Answer 16

The greater the difference in concentration, the faster the rate of diffusion.

Question 17

Diffusion

Answer 17

No energy required

Movement of particles in a solution or gas from a higher to a lower concentration.

Example: Oxygen and Carbon dioxide in gas exchange.

Factors that affect the rate:
- concentration
- surface area
- temperature

Question 18

Osmosis

Answer 18

No energy required

Movement of water from a concentrated solution to a dilute solution through a semi permeable membrane

Example: Plants absorb water from the soil by osmosis through their root hair cells. Plants use water for several vital processes, including photosynthesis and transporting minerals.

Question 19

Active transport

Answer 19

Energy required

Movement of particles from a dilute solution to a more concentrated solution

Examples: movement of mineral ions into roots of plants, movement of glucose into the small intestines.

Question 20

Adaptations for diffusion in Small Intestines

Answer 20

Villi - increase surface area
Good blood supply - to maintain concentration gradient
Thin membranes - short diffusion distance.

Question 21

Adaptations for diffusion in the lungs

Answer 21

Alveoli - increase surface area
Good blood supply - to maintain concentration gradient
Thin membranes - short diffusion distance.

Question 22

Adaptations for diffusion in the gills of fish (why we need to know this is a mystery)

Answer 22

Gill filaments and lamelia - increase surface area
Good blood supply - to maintain concentration gradient
Thin membranes - short diffusion distance.

Question 23

Adaptation for diffusion in roots

Answer 23

Root hair cells - increase surface area.

Question 24

Adaptation for diffusion in leaves

Answer 24

Large surface area
Thin leaves for short diffusion path
Stomata on the lower surface to let oxygen and carbon dioxide in and out.