Bio Paper 2 Flashcards
Why does incomplete combination occur? 
because it’s not enough oxygen for complete combustion 
What is the equation for photosynthesis? (symbol)
6CO2 + 6H2O -> C6H12O6 + 6O2
What are the control variables in a photosynthesis practical?
Temperature, concentration of sodium hydrogencarbonate, type of weed and mass of weed
Describe how you would test to see how light intensity affects the rate of photosynthesis? (6 marks)
- put pond weed and sodium hydrogen carbonate in a beaker with a bung
- connect gas syringe onto beaker
- put light source a set distants away and use a stopwatch to time 10 minutes
- gas syringe will show am out of oxygen produced
- oxygen produced / time = cm3/min
- control = temp / conc of sodium / weed / mass of weed
- repeat at different distances to compare the affect of light intensity
Describe the difference between the phloem and the xylem (6 marks)
Phloem:
- living
- transfers food
- process = translocation
- requires energy
- has end walls
Xylem:
- dead
- transports water and minerals
- only transfers up
- process = transpiration
- no end walls
How does transpiration occurs (3 marks)
- Evaporation ( diffusion out stomata)
- xylem
- ## absorption
What increases transportation?
- increase in light intensity
- increase in temperature
- increase in air flow
How would you measure rate of transportation (6 marks)
- use a potometer with a plant at the top and a beaker of water at the bottom
- use a ruler and put it at a air bubble
- start a stop watch for 10 minutes
- record distance the air bubble traveled
- distance / time = mm/min
- repeat by turning tap on reservoir of water to put air bubble back
What diffuses out of stomata?
CO2, H2O and O2
What do guard cells do?
Change shape to open and close stomata (when turgid it’s open - when flaccid it closed)
What are the layers of a leaf? (4 marks)
- upper epidermis (waxy)
- palisade mesophyll tissue
- spongy mesophyll tissue
- lower epidermis
What are all the adaptations of leaves (6 marks)
- large surface area
- palisade layer near top for light
- upper epidermis is transparent so light can get to palisade layer
- xylem and phloem for water and to transport glucose as slucose
- waxy layer reduces water loss
- sponge mesophyll contains air gaps to increase rate of diffusion
- lower epidermis has lots of stomata to let CO2 diffuse in
What do select weed killers do?
- they are developed from auxins
- affect broad leaves
- disrupts growth pattern-> killing it
Why would you grow from cutting root powder?
- contains auxins
- produces rapid clones
How and why do you control flowering for fruit formation? (3 marks)
- gibberlellins stimulate seed germination and stem cells
- plants can flower earlier in a hasher condition
- this reduces flowers formation
- improving fruit quality
How do you make seedless fruit?(1 mark)
Add gibberelins to unpollinated flower and only fruit will grow
Why and how do we control ripening of fruit? (2 marks)
- Allows fruit to travel before ripe so there is less damage
- ethene is added on the way to store
Why and how do we control seed germination? (2 marks)
- to make seeds germinate any time
- helping batches grow all together
- use gibberellins
What does the pituitary gland do? (3 marks)
- produces many hormones
- regulates body conditions
- directs other glands to release hormones
What does the thyroid gland do? (2 marks)
- produces thyroxine
- regulates (metabolism/heart rate/temperature)
What does the pancreas do? (2 marks)
- produces insulin
- regulates blood glucose
Describe the endocrine glands (4 marks)
- the do constant adjustments to the body
- slow action
- long lasting
- works in a generally area of body
- travels through the blood
Describe how adrenaline works (6 marks)
- adrenaline binds to receptors in heart
- causes muscles to contract with more force (increasing blood pressure)
- increasing the blood flow so muscle can reserve O2 and glucose for respiration
- adrenaline binds to liver causing break down of glycogen
- this releases glucose increasing blood glucose levels
- this means more glucose can get to cells
How does thyroxine regulate metabolism? (4 marks)
- when blood thyroxine levels are too low
- hypothalamus releases TRH that stimulates the pituitary gland to release TSH
- This stimulates thyroid gland to release thyroxine until levels are too high
- TRH from hypothalamus is inhibited with reduces TSH so blood thyroxine levels fall
In the menstrual cycle what does FSH do? (4 marks)
- cause egg to mature
- follical stimulating hormone
- is realised from pituitary gland
- stimulates production of oestrogen
What does oestrogen do in the menstrual cycle? (2 marks)
- Thicken the uterus lining
- stimulates a rapid production of LH
What does LH do in the menstrual cycle? (3 marks)
- produced by pituitary gland
- releases egg
- stimulates remains of follide to develop a corpus luteum
What does the corpus luteum do in the menstrual cycle? (3 marks)
- produces progesterone
- which maintains uterus lining
- also stops production of FSH and LH
What happened when progesterone falls and there’s a low oestrogen level? (2 marks)
- lining breaks down
- FSH is released and cycle starts again
What does clomifene therapy do? (2 marks)
- if you can’t reproduce naturally
- produces FSH and LH
- alows egg to be produced
What is IVF used for (1 mark)
- forming embryo in a lab for someone that can’t reproduce
What does progesterone do in the mini pill or injection? (2 marks)
- build cerrical mucus
- acts as a barrier
That does oestrogen do in the combined pill? (1 mark)
- inhibits FSH stopping egg maturing