b2.3- cell specialisation

Question 1

impact of gradients on gene expression within an early-stage embryo

Answer 1

• cells are unspecialised at first
• as embryo grows, the cells develop along different pathways and become specialised for different functions
• becomes more efficient

Question 2

definition of stem cells

Answer 2

• cells capable to carry out cell division
• not differentiated into specialised cell yet

Question 3

stems cells function [2]

Answer 3

1. differentiate along different pathways
2. retains the capacity to divide

Question 4

totipotent

Answer 4

can become any cell type or a single organism
eg. zygote cells

Question 5

pluripotent

Answer 5

any type but not a single organism
eg. embryonic stem cells

Question 6

multipotent

Answer 6

similar group of cells
eg. bone marrow -> various blood cells

Question 7

unipotent

Answer 7

only one cell type
eg. liver (can regenerate)

Question 8

nullipotent

Answer 8

cannot divide
eg. red blood cells

Question 9

location of function of hair follicles

Answer 9

to grow hair

Question 10

location and function of bone marrow

Answer 10

center of most bones and in the end of spongy bones
creates blood cells and platelets for your blood

Question 11

why growing cells tend to divide and remain small

Answer 11

maintain high SA:vol ratio
- fast exchange of nutrients, small distance
- reaction would generate heat

Question 12

when size of a cube increases- SA:vol ratio

Answer 12

decreases drastically
eg. 1x1x1 cube
SA= 6 cm2
vol=1 cm3
ratio= 6:1

2x2x2 cube
SA= 24 cm2
vol= 8 cm3
ratio= 3:1

Question 13

autotroph

Answer 13

an organism that can produce its own food

Question 14

heterotroph

Answer 14

an organism that eats other plants or animals for energy and nutrients

Question 15

another term for red blood cell

Answer 15

erythrocytes

Question 16

adaptations to increase SA:vol ratio [5]

Answer 16

1. flattening
   eg. erythrocytes
   - biconcave shape
2. microvilli
   eg. proximal convoluted tubule (first bit of the nephron tubule)
   - distance (folds) + speed (lots of turns so slower) : more time to get all the glucose back
3. invaginations/ folds
   eg. cristae in mitochondria
4. compartmentalisation
5. maintain concentration gradient

Question 17

function of ATI

Answer 17

diffusion of oxygen and carbon dioxide (gas exchange)- passive process

Question 18

adaptations of ATI

Answer 18

• very thin
• distance over where oxygen and carbon dioxide must diffuse is very small

Question 19

function of ATII

Answer 19

• makes and store phospholipid

Question 20

adaptations of ATII

Answer 20

• rough er- make phospholipid
• vesicle- release phospoholipid

Question 21

functions of striated muscle cells

Answer 21

movement
- doesnt need to be fast/ in unison

Question 22

adaptations of striated muscle cells

Answer 22

• unbranched

Question 23

function of cardiac muscle cells

Answer 23

to pump blood around body in using electrical signal in a particular rhythm

Question 24

adaptation of cardiac muscle cells [3]

Answer 24

1. branched
   - so electrical impulses can spread very fast
2. joined end to end
3. myogenic

Question 25

adaptation of an egg [2]

Answer 25

1. zoda pellucida- very thick
   - makes sure only one sperm can enter
2. thick cytoplasm
   - contain a lot of nutrients to make embryo

Question 26

function of sperm

Answer 26

transfer a haploid nucleus form the testis of a male to the cytoplasm of an egg cell in the oviduct of a female

Question 27

adaptation of sperm [4]

Answer 27

1. acrosome (enzyme)- digest zona pellucida
2. change protein on the zona pellucida so other sperm’s acrosomes wont work (enzymes are specific)
3. long tail- adapted to swim fast to the egg
4. many mitochondria
   - provide ATP to ensure that the sperm can get to the egg

Question 28

rate of diffusion is proportional to

Answer 28

surface area

Question 29

rate of metabolism is proportional to

Answer 29

volume

Question 30

why small cells are more efficient than big cells

Answer 30

• higher SA:vol ratio
• diffusion distance short, less time needed

Question 31

special feature of a giant alga that is an exception to the cell theory

Answer 31

lacks subdivision into separate cells