Cell Biology

Question 1

what makes a cell eukaryotic?

Answer 1

it has its genetic material inside of a nucleus

Question 2

what makes a cell prokaryotic?

Answer 2

it’s genetic material is not inside of a nucleus

Question 3

what are the three main features of a eukaryotic cell?

Answer 3

1. nucleus
2. cell membrane
3. cytoplasm

Question 4

where is the dna stored within a prokaryotic cell?

Answer 4

1. the loop of dna
2. the plasmids

Question 5

what are the five main features of a prokaryotic cell?

Answer 5

1. loop of dna
2. plasmids
3. cell wall
4. cell membrane
5. cytoplasm

Question 6

give an example of a eukaryotic cell

Answer 6

animal
OR
plant
OR
fungi
OR
protista

Question 7

give an example of a prokaryotic cell

Answer 7

bacterial

Question 8

describe what the cell membrane does

Answer 8

controls the substances that come into and out of the cell

Question 9

describe what the nucleus does

Answer 9

controls the activities of a cell

Question 10

describe what the mitochondria do

Answer 10

it’s where aerobic respiration takes place

Question 11

describe what the ribosomes do

Answer 11

proteinsynthesis

Question 12

describe what the cytoplasm does

Answer 12

it’s where the chemical reactions take place

Question 13

describe what chloroplasts do

Answer 13

the chlorophyll within them absorbs light for photosynthesis

Question 14

describe what the vacuole is and what it does

Answer 14

it’s filled with cell sap and helps the plant cell keep it’s shape

Question 15

describe what the cell wall is and what it does

Answer 15

it’s made from cellulose and strengthens the cell

Question 16

magnification equation

Answer 16

magnification = image size
——————
real size

Question 17

define differentiation

Answer 17

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

Question 18

examples of specialised cells are…

Answer 18

sperm cell, nerve cell, muscle cell

Question 19

how is a sperm cell adapted for its function? (5)

Answer 19

• streamlined head to help it swim to the egg
• digestive enzymes in the head to penetrate the egg
• dna stored within nucleus to produce offspring
• mitochondria to release energy for the swim to the egg
• tail to help it swim to the egg

Question 20

what is the function of a nerve cell?

Answer 20

to send electrical impulses around the body

Question 21

how is a nerve cell specialised for its function? (4)

Answer 21

• long axon to carry the electrical impulses from one body part to another
• myelin insulates the axon and speeds up the transmission of electrical impulses
• synapses on the end which have junctions to allow the impulse to pass from one nerve cell to the other
• dendrites give it a large surface area so other nerve cells can connect more easily

Question 22

how is a muscle cell adapted to its function? (3)

Answer 22

• protein fibres for contractions
• many mitochondria to provide the energy for contractions
• cells store glycogen for respiration

Question 23

how is a root hair cell adapted for its function? (2)

Answer 23

• large permanent vacuole to speed up osmosis
• many mitochondria to release energy for the active transport of mineral ions

Question 24

how is xylem adapted for its function? (2)

Answer 24

• long, hollow tubes for easy movement of water and minerals
• spirals of lignin which help strengthen the cells and support the plant

Question 25

how is phloem adapted to its function? (2)

Answer 25

- cell walls have sieve plates to allow dissolved food to move easily - many mitochondria to release energy for movement of food

Question 26

what is a **stem cell**?

Answer 26

an undifferentiated cell that can give rise to more cells of the same type and differentiate to form other types of cells

Question 27

what is an **embryonic stem cell**?

Answer 27

something that can differentiate into any other type of body cell

Question 28

what is an **adult stem cell**?

Answer 28

something that can only differentiate to form cells found in the blood (e.g. red blood cells, white blood cells, platelets)

Question 29

what is **therapeutic cloning**?

Answer 29

- where an embryo is made to have the same genetic information as the patient - the stem cells produced will therefore also have the same genetic information - the patients body won’t reject them when they enter the body during a transplant

Question 30

define **diffusion**

Answer 30

the movement of particles from an area of higher concentration to an area of lower concentration

Question 31

what are the three factors that affect the rate of diffusion?

Answer 31

**concentration gradient** - the greater the concentration gradient, the faster diffusion will take place **temperature** - the higher the temperature, the greater the rate of diffusion **surface area** - the larger the surface area, the greater the rate of diffusion

Question 32

how are gills adapted for gas exchange? (4)

Answer 32

- each gill is made of thin plates called **gill filaments** which give a large surface area - gill filaments are covered in **lamellae** which give the gills and even larger surface area - **lamellae** have lots of blood capillaries, providing good blood supply - have a **thin surface layer of cells** to lessen the distance that the gases have to travel

Question 33

define **osmosis**

Answer 33

the movement of water particles from an area of high water concentration to an area of low water concentration through a partially permeable membrane

Question 34

define **active transport**

Answer 34

the movement of particles from an area of lower concentration to an area of higher concentration

Question 35

what is the difference between diffusion and active transport?

Answer 35

active transport requires energy from respiration to make it work whilst diffusion doesn’t

Question 36

what are chromosomes?

Answer 36

coiled up lengths of dna molecules

Question 37

define **the cell cycle**

Answer 37

where body cells in multicellular organisms divide to produce new cells

Question 38

what are the three stages of the cell cycle?

Answer 38

1. growth 2. dna replication 3. mitosis

Question 39

explain the **growth** stage of the cell cycle (2)

Answer 39

- in an undivided cell, the dna is spread out in long strings and the small space within the cell isn’t enough to hold them - cell has to grow and also increase the amount of sub-cellular structures to be able to provide for the new cell

Question 40

explain the **dna replication** stage of the cell cycle (2)

Answer 40

- dna is duplicated so that there’s one copy for each cell - they both have exactly the same dna in each ‘arm’ of the x-shaped chromosome

Question 41

explain the **mitosis** stage of the cell cycle (5)

Answer 41

- chromosomes line up in the centre of the cell - cell fibres pull the chromosomes apart, splitting the two arms down the middle and pulling them to opposite sides of the cell - cell membranes form around the sets of chromosomes - these cell membranes become the nuclei of the two new cells - cell membrane and cytoplasm divide

Question 42

how many daughter cells are produced by mitosis?

Answer 42

two

Question 43

give two ways embryonic stem cells can be used to cure disease

Answer 43

1. can make insulin-producing cells for someone with diabetes 2. can make nerve cells for someone that is paralysed by spinal injuries

Question 44

where are stem cells found in a plant?

Answer 44

the meristems

Question 45

what can the stem cells be used to do within plants? (3)

Answer 45

- to produce clones of whole plants quickly and cheaply - to grow more plants of rare species to save them from extinction - can also be used to grow crops of identical plants that have desired features for farmers (disease resistance)