cell structure and function

Question 1

what is the function of the nucleus of a cell

Answer 1

1. control cell activities such as cell growth and the repair of worn-out parts
2. contain genetic information in the form of chromosomes to allow for cell division

Question 2

what is the nuclear membrane

Answer 2

a membrane that separates the contents of the nucleus from the rest of the cytoplasm and has 2 layers of membranes

Question 3

what is the function of the rough endoplasmic reticulum

Answer 3

it modifies the proteins made by the ribosomes that are attached to its outer surface

Question 4

how to identify rough endoplasmic reticulum

Answer 4

ribosomes attached to outer surface
outer surface continuous with nuclear envelope
flattened

Question 5

what is the function of ribosomes

Answer 5

synthesis proteins in the cell (ribosomes attached to the RER make proteins that are transported out the cell, ribosomes lying freely in the cytoplasm make proteins used within the cytoplasm)

Question 6

function of the smooth endoplasmic reticulum

Answer 6

1. synthesise substances such as fats and steroids
2. convert harmful substances into harmless ones through the process of detoxification

Question 7

how to identify smooth endoplasmic reticulum

Answer 7

does not have ribosomes attached to its surface
tubular

Question 8

function of the mitochondria (singular: mitochondrion)

Answer 8

site of aerobic respiration to produce ATP for cellular activities

Question 9

how to identify mitochondrion

Answer 9

presence of double membranes (that surround a matrix)
inner membranes fold inwards to form cristae

Question 10

function of the Golgi body

Answer 10

1. chemically modify substances made by the endoplasmic reticulum
2. stores and packages substances in vesicles for secretion out the cell or to other organelles in the cell

Question 11

how to identify Golgi body

Answer 11

comprises cup-shaped series of compartments (cisternae)

Question 12

function of cytoplasm

Answer 12

jelly-like substance where most cell activities occur

Question 13

function of cell surface membrane

Answer 13

partially permeable membrane that controls the movement of substances in and out of the cell

Question 14

function of cellulose cell wall

Answer 14

protects cell from injury and gives the plant cell a fixed shape

Question 15

function of chloroplast

Answer 15

contain chlorophyll that traps light that is used for photosynthesis to make food for the cell

Question 16

how to identify chloroplast

Answer 16

presence of double membrane (encloses a fluid filled space called stroma)

Question 17

function of vacuole

Answer 17

stores substances within the cell
plant cell: large central vacuole that contains sugar, mineral salts and amino acids or serves as disposal of waste materials
animal cell: numerous small vacuoles that exist temporarily and store water and food substances

Question 18

how are substances made by the endoplasmic reticulum moved out of the cell

Answer 18

1. vesicles containing polypeptides made by the rough endoplasmic reticulum pinch off from it
2. vesicles fuse with the Golgi body and release the molecules made by the rough endoplasmic reticulum inside. they may be modified by the Golgi body
3. secretory vesicles containing such modified molecules pinch off from the Golgi body and move towards the cell surface membrane
4. secretory vesicles fuse with the cell surface membrane and their contents exit the cell

Question 19

types of specialised cells

Answer 19

red blood cell, root hair cell, skeletal muscle cell

Question 20

definition of differentiation

Answer 20

the process by which a cell becomes specialised for a specific function

Question 21

structural features of red blood cells

Answer 21

1. contain haemoglobin
2. have a circular, biconcave shape
3. lack a nucleus
4. flexible / elastic

Question 22

why do red blood cells contain haemoglobin

Answer 22

haemoglobin binds to oxygen easily allowing red blood cells to transport of oxygen around the body

Question 23

why do red blood cells have a biconcave shape

Answer 23

it increases the surface area to volume ratio of the cell so that oxygen can diffuse in and out of the cell at a higher rate

Question 24

why do red blood cells lack a nucleus

Answer 24

to contain more haemoglobin for the transport of oxygen

Question 25

why are red blood cells flexible / elastic

Answer 25

allows the cell to change shape easily and squeeze through narrow blood capillaries easily

Question 26

structural features of root hair cell

Answer 26

1. has a long and narrow extension
2. low water potential in cell (not really structural feature but)

Question 27

why do root hair cells have long and narrow extensions

Answer 27

increases the surface area-to-volume ratio for the cell to absorb water and mineral salts at a higher rate

Question 28

why do root hair cells have a low water potential

Answer 28

increase the rate of osmosis of water into the root hair cell

Question 29

structural features of skeletal muscle cells

Answer 29

1. elongated and cylindrical in shape
2. contain many mitochondria
3. contain many nuclei

Question 30

why are skeletal muscle cells elongated and cylindrical in shape

Answer 30

to contain contractile protein fibres

Question 31

why do skeletal muscle cells contain many mitochondria

Answer 31

to provided more energy for the contraction of the muscle cell

Question 32

why do skeletal muscle cells contain many nuclei

Answer 32

allows the cells to acquire more oxygen and nutrients to produce more energy