Unit 2 - Cell organisation and stem cells

Question 1

Define cell

Answer 1

a single repeating unit of an organism

Question 2

Define tissue

Answer 2

a collection of differentiated cells that have a common function

Question 3

Define organ

Answer 3

a group of tissues that work together to carry out a common function

Question 4

Define organ system

Answer 4

a group of organs that carry out a common function

Question 5

Define specialised

Answer 5

having particular structure to serve a particular function

Question 6

Define differentiated

Answer 6

the process by which a less specialised cell develops a distinct form and function,a cell specialising

Question 7

Why do multicellular organisms need specialised cells?

Answer 7

• complex communication in a multicellular organism
• specialised functions need specialised cells
• maximise efficiency of processes like absorbing nutrients

Question 8

What features does an erythrocyte have to suit it for its function?

Answer 8

Biconcave disc- maximises SA to carry oxygen
No nucleus- more room for haemoglobin
Flexible- can squeeze through narrow capillaries

Question 9

What features does a neutrophil have to suit it for its function?

Answer 9

Multilobed nucleus- makes it easier for neutrphils to squeeze through small gaps
Granular cytoplasm- contains many lysosomes which contain enzymes used to attack pathogens

Question 10

What features does a root hair cell have to suit its function?

Answer 10

Root hairs- increase surface area to maximise uptake of water/minerals from the soil

Question 11

What features does a sperm cell have to suit it for its function?

Answer 11

Mitochondria- supplies the energy to swim
Tail- allows for movement
Acrosome- contains digestive enzymes which digest protective layers around ovum

Question 12

What features does a palisade cell have to suit it for its function?

Answer 12

Chloroplasts- absorb a large amount of light
Rectangular- packs closely to form a continuous layer
Chloroplasts are able to move in cytoplasm- so can absorb more light

Question 13

What features does a guard cell have to suit it for its function?

Answer 13

Cell wall thicker on inside than outside- so cell doesn’t change symmetrically as its volume changes
Gap in the centre- allows gases in and out

Question 14

What are the 4 main categories of tissues in animals?

Answer 14

Nerve tissue
epithelial tissue
muscle tissue
connective tissue

Question 15

What are stem cells?

Answer 15

Undifferentiated cells with the potential to differentiate into a variety of the specialised cell types of an organism

Question 16

Define undifferentiated

Answer 16

An unspecialised cell originating from mitosis or meiosis

Question 17

Define potency

Answer 17

the ability of a stem cell to differentiate into different cell types

Question 18

Define totipotent

Answer 18

A stem cell that can differentiate into any type of cell (including extra-embryonic) and form a whole organism

Question 19

Define pluripotent

Answer 19

a stem cell that can form all types of tissue but not a whole organism

Question 20

Define multipotent

Answer 20

can only form a range of cells from a certain cell lineage

Question 21

Give an example of where totipotent cells are found in a human

Answer 21

In a zygote

Question 22

Give an example of where pluripotent cells are found in a human

Answer 22

Blastocyst

Question 23

Give an example of where multipotent cells are found in a human

Answer 23

Blood stem cells

Question 24

What are the characteristics of stem cells?

Answer 24

• can repeatedly undergo cell division
• not adapted to a specific function
• can give rise to specialist cells
• few epigenetic markers

Question 25

What are stem cells used for in the body?

Answer 25

• growth
• development (of am embryo)
• tissue repair

Question 26

Where are stem cells found in plants?

Answer 26

Vascular cambium
Meristematic tissue (e.g roots and shoots)

Question 27

How do cells become specialised?

Answer 27

• all cells have the same DNA
• genes are switched on and off by epigenetics
• different proteins are produced in the cell
• so the cell can undergo a specialised function due to the proteins

Question 28

How long do erythrocytes live for?

Answer 28

120 days

Question 29

How long do neutrophils live for?

Answer 29

6 hours