Topic 1 - Cell biology

Question 1

Name 5 subcellular structures that both plant and animal cells have (and their purpose)

Answer 1

Nucleus - contains DNA
Cytoplasm - where chemical reactions happen
Cell membrane - controls what goes in and out
Mitochondria - where respiration happens (transfers energy)
Ribosomes - where proteins are made

Question 2

Name 3 subcellular structures that just plant cells have (and their purpose)

Answer 2

Cell wall - supports cell
Vacuole - contains cell sap
Chloroplasts - where photosynthesis occurs

Question 3

Are plant and animal cells prokaryotic or eukaryotic?

Answer 3

Eukaryotic

Question 4

Are bacteria cells prokaryotic or eukaryotic?

Answer 4

Prokaryotic

Question 5

Define cells

Answer 5

Cells are basic units that make up a living organism

Question 6

State some similarities between prokaryotic and eukaryotic cells

Answer 6

They both have DNA, a cell wall, ribosomes and a cell membrane

Question 7

State some differences between prokaryotic and eukaryotic cells

Answer 7

E has its DNA enclosed in a nucleus whereas P is just in its cytoplasm.
E is complex and uni or multicellular whereas P is simpler and always unicellular (and smaller)

Question 8

Define magnification

Answer 8

how much bigger a sample appears to be under the microscope than it is in real life

Question 9

Define resolution

Answer 9

the ability to distinguish between two points on an image - the amount of detail

Question 10

What is the formula for magnification?

Answer 10

magnification = image/actual size

Question 11

Define aseptic technique

Answer 11

taking steps to avoid contamination from pathogens

Question 12

Define diploid

Answer 12

A full set of chromosomes (46)

Question 13

Define chromatid

Answer 13

A copy of a chromosome

Question 14

Explain the growth and DNA replication stage of the cell cycle

Answer 14

The DNA is spread out in long strings. It grows and increases the amount of subcellular structures it has. It then duplicates its DNA so there’s one copy for each new cell, creating an X-shaped chromosome

Question 15

Explain the mitosis stage of the cell cycle

Answer 15

The chromosomes line up at the centre of the cell and cell fibres pull them apart to opposite ends of the cell. Membranes form around each of the new sets of chromosomes. The cell has produced two daughter cells (which are identical to each other and to the parent cell).

Question 16

How are stem cells different to regular cells?

Answer 16

They are non-specialised so they can become any cell

Question 17

How are adult and embryonic stem cells different?

Answer 17

Embryonic stem cells can become any cell but adult stem cells can only become some cells

Question 18

Name some sources of human stem cells:

Answer 18

-embryos
-bone marrow
-therapeutic cloning

Question 19

Define differentiation

Answer 19

the process by which a cell changes to become specialised for its job

Question 20

Give two uses of stem cells in animals

Answer 20

-treat diseases
-replace organs/tissues

Question 21

Give two uses of stem cells in plants

Answer 21

-grow rare species
-improve features of plants

Question 22

Give reasons for and against embryonic stem cells

Answer 22

For:
-legally still just a bunch of cells
-could find cures
-could replace humans in testing processes (e.g for new drug)
Against:
-destroys a potential life
-no-one dies if you use adult stem cells

Question 23

Define diffusion

Answer 23

the movement from an area of high concentration to an area of low concentration (down a concentration gradient)

Question 24

How does distance affect the rate of diffusion?

Answer 24

if the particles have to travel further, it’s going to take longer and the particles are going to lose energy so rate of diffusion is slowed

Question 25

How does concentration gradient affect the rate of diffusion?

Answer 25

when there’s a larger concentration gradient, there are more particles which means more energy which means faster diffusion

Question 26

How does surface area affect the rate of diffusion?

Answer 26

when there’s a bigger surface area, there are more places for the particles to move into which means more particles can diffuse at the same time

Question 27

How does temperature affect the rate of diffusion?

Answer 27

higher temp means more energy so the particles will move faster

Question 28

Name the 4 common features of all exchange surfaces:

Answer 28

-big surface area
-thin (short distance for diffusion)
-moist (allows substances to dissolve)
-a means of maintaining a steep concentration gradient to speed up diffusion

Question 29

Define concentration gradient

Answer 29

the difference in concentration between two areas

Question 30

Define osmosis

Answer 30

the diffusion of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
- [mention water 3 times]

Question 31

Define a partially permeable membrane

Answer 31

it has small holes in it that permit small water molecules through

Question 32

Define dilute

Answer 32

Dilute solutions have a high concentration of water molecules

Question 33

Define concentrated

Answer 33

Concentrated solutions have a low concentration of water molecules

Question 34

What would happen if a blood cell was put it in distilled water?

Answer 34

It would swell and burst because the water molecules would diffuse into the cell so they can move away from the high water concentration outside and into the low water concentration inside

Question 35

What would happen if a blood cell was put in a concentrated solution?

Answer 35

It would shrink and shrivel because water would diffuse out of the cell because the is a lower water concentration outside the cell so it moves from a higher water concentration inside the cell

Question 36

What is the formula for calculating percentage mass?

Answer 36

change/original value x 100