Cell biology bbc bitesize

Question 1

microscope labels

Answer 1

eye piece
coarse focus - the stage is as close to the objective lens as possible.
fine focus
objective lens
stage clip
condenser
mirror
arm
stage

Question 2

what are the aims of experiment for Preparing biological samples for examination

Answer 2

To stain cells for examination with a light microscope.
To examine a range of cells and other structures with a microscope to understand their basic structure.

Question 3

Risks for Preparing biological samples for examination

Answer 3

Care must be taken when looking down the microscope if the illumination is too bright.
Care when using microscope stains.
Care when handling coverslips, microscope slides and mounted needles.

Question 4

xylem structure

Answer 4

There are no top and bottom walls between xylem vessels, so there is a continuous column of water running through them. Their walls become thickened and woody. They therefore support the plant.

Question 5

phloem structure

Answer 5

Dissolved sugars/amino acids can be transported both up & down the stem. Companion cells, adjacent to the sieve tubes provide energy required to transport substances in the phloem.

Question 6

Cells of the Circulatory system are specialized to?

Answer 6

Transport substances, defend the body, regulate temperature

Question 7

cells of the excretory system are specialized to?

Answer 7

Remove waste products and unwanted substances, regulate the water content of the body

Question 8

cells of the musclar system are specialized to?

Answer 8

bring about movement

Question 9

cells of the nervous system are specialized to?

Answer 9

Respond to internal and external stimuli and conditions, carry messages for the body work as a coordinated whole

Question 10

cells of the Respiratory system are specilised to?

Answer 10

Deliver oxygen for respiration and remove waste

Question 11

cells of the Reproductive system are specilised to?

Answer 11

Bring about fertilisation to produce new offspring

Question 12

cells of the Skeletal system are specialized to?

Answer 12

To bring about movement, support and protect internal structures, produce blood cells, store and release calcium

Question 13

Adult stem cells can be found in several regions of the body, including the:

Answer 13

brain
eyes
blood
heart
liver
bone marrow
skin
muscle

Question 14

where does cell division in plants occur?
what can meristems produce?
where are the main meristems located?

Answer 14

regions called meristems.
can differentiate to produce all types of plant cells at any time during the life of the plant.
close to the tip of the shoot, and the root.

Question 15

what happens in growing shoots?
what happens as the cells become older?

Answer 15

new cells are being produced continuously near the tip. they become differentiated they enlarge and develop vacuoles.

Question 16

how can plant cells be cloned?

Answer 16

Meristematic cells are removed from a plant & grown in tissue culture, containing agar – to provide support & water for the growing cells – along with nutrients & plant hormones to stimulate growth/ cell division.

Question 17

why are plants cloned?

Answer 17

Plants are cloned to produce identical plants quickly and economically.

Question 18

why do we clone plants?

Answer 18

is quicker than allowing plants to reproduce &collecting & sowing seeds. It’s an effective way of producing new individuals from endangered plants, preserving species.

Question 19

why is it useful for clones being genetically identical to the original plant?

Answer 19

to provide crop plants for large cultivation that have desirable characteristics e.g. disease resistance.

Question 20

what is the process of growth & DNA replication?

Answer 20

1) the DNA is all spread out in long strings
2) before it divides, the cell has to grow & increase the amount of sub-cellular structures,
3) it then duplicates its DNA

Question 21

What is binary fission?

Answer 21

how prokaryotic cells replicate

Question 22

what are the stages of binary fission?

Answer 22

1) circular DNA & plasmids replicate
2)cell gets bigger & the circular DNA strands move to opposite ends of the cell
3)the cytoplasm begins to divide & new ell walls begin to form
4) cytoplasm divides & 2 daughter cells are porduced. each daughter cell has one copy of the circular dna, but has a variable number of copeis of the plasmids.

Question 23

what diseases can be treated by stem cells?

Answer 23

in type 1 diabetes
in cases of multiple sclerosis, which can lead to paralysis
in cases of spinal cord or brain injury, that have led to paralysis

Question 24

what is therapeutic cloning?

Answer 24

produces stem cells with the same genetic make-up as the patient. The technique involves transfer of the nucleus from a cell of the patient, to an egg cell whose nucleus has been removed.

Question 25

issues with stem cells

Answer 25

• human embryos are a potential human life
  -using existing patients is more important than the rights of embryos

Question 26

examples of diffusion?

Answer 26

• in a leaf
  -in the lungs
• liver cells

Question 27

osmosis in red blood cells?

Answer 27

lose water and shrink
gain water, swell and burst in a more dilute solution

Question 28

what happens if a red blood cell gains/loses too much water?

Answer 28

if cells lose or gain too much water by osmosis, they do not function efficiently

Question 29

Active transport in animals

Answer 29

glucose molecules move across the gut wall into the blood, it needs to be absorbed. When the glucose conc. in the intestine is lower than the intestinal cells, glucose moves via active transport.

Question 30

where is epithelia found and what structural function does it have?

Answer 30

the epithelia of alveoli in the respiratory system and the villi in the small intestine are only one cell thick

Question 31

The human lungs provide an exchange surface adapted for:

Answer 31

absorbing oxygen – needed for respiration – into the blood from the air
transferring carbon dioxide – produced by respiration – from the blood into the lungs then the air

Question 32

what are the lungs what is their function?

Answer 32

organs enclosed within the chest/thorax. Air needs to be breathed in to be brought into contact with the exchange surfaces within the lungs. This process is called ventilation.

Question 33

what is the structure of the respiratory system?

Answer 33

-lungs enclosed in the thorax, surrounded by 12 pairs of ribs.
-ribs are moved by 2 sets of intercostal muscles.
-lungs are sealed within 2 airtight pleural membranes. This wraps round the lungs & line the rib cage.
-trachea/windpipe, branches into two bronchi. Rings of cartilage in the walls of the trachea help to keep it open as air is drawn in.
-bronchi split in smaller branches to bronchioles. they end in a cluster of air sacs called alveoli.

Question 34

Exchange of gases in fish is very efficient because of:

Answer 34

• large surface area of the gills
  -large surface area of capillaries in each gill filament
• short distance for diffusion – the outer layer of the gill filaments & capillary walls are 1 cell thick
• efficient ventilation of the gills with water
• moving blood & ventilated gill surfaces mean that gases exchanged are continually removed

Question 35

how is a high concentration gradient maintained in the gills of a fish?

Answer 35

moving blood & ventilated gill surfaces mean that gases exchanged are continually removed – oxygen enters the blood, & CO2 removed to the water.

Question 36

why is gas exchange more difficult for fish than animals on land?

Answer 36

The conc. of oxygen in water is dependent on the temperature of the water.