paper 3 Flashcards
Explain why a thicker medulla means a greater concentration of urine (3) [2019]
- thicker medulla means a longer loop of henle
- increased Na+ conc in medulla
- water potential gradient maintained for longer so more water reabsorbed
Describe the role of saprobionts in the nitrogen cycle (2) [2019]
- decompose proteins and DNA
- converts this into ammonia
One environmental issue arising from the use of fertilisers is eutrophication.
Eutrophication can cause water to become cloudy.
You are given samples of water from three different rivers.
Describe how you would obtain a quantitative measurement of their cloudiness (3) [2019]
- use a colorimeter
- measure the absorbance
- same volume of water sampled
When counting white blood cells, the doctor only diluted the blood sample by a factor
of 20 times, instead of 200 times when counting red blood cells.
Suggest why he only diluted the sample by a factor of 20 times. (1) [2018]
there are fewer white blood cells so no need to dilute further
Determining the genome of the viruses could allow scientists to develop a vaccine. Explain how. (2) [2020]
- identify proteins/ proteome
- identify antigens to use in the vaccine
EPO is another performance-enhancing drug. It can increase the haematocrit (the percentage of red blood cells in blood).
A heart attack is caused by a lack of glucose and oxygen being delivered to cardiac muscle via the coronary arteries. The overuse of EPO can increase the risk of a heart attack.
Suggest how. (2) [2020]
- EPO causes the blood to thicken
- Thickened blood could block coronary arteries
