AQA A-Level Biology long answer Qs
Glucose is absorbed from the lumen of the small intestine into epithelial
cells. Explain how the transport of sodium ions is involved in the absorption
of glucose by epithelial cells. (5 marks) [Unit 1, June 16]
1. Na+ ions leave epithelial cell and enter blood;
2. (Transport out is by) active transport / pump / via carrier protein using
ATP;
3. So, Na+ conc. in cell is lower than in lumen (of gut);
4. Sodium/Na+ ions enter by FACILITATED diffusion;
5. Glucose absorbed with Na+ ions against their concentration/diffusion
gradient / glucose absorbed down an electrochemical gradient;
Oxygen and chloride ions can diffuse across cell-surface membranes. The
diffusion of chloride ions involves a membrane protein. The diffusion of
oxygen does not involve a membrane protein.
Explain why the diffusion of chloride ions involves a membrane protein and
the diffusion of oxygen does not. (5 marks) [Unit 1, June 16]
1. Chloride ions water soluble/charged/polar;
2. Cannot cross (lipid) bilayer (of membrane);
3. Chloride ions transported by facilitated diffusion OR diffusion involving
channel/carrier protein;
4. Oxygen not charged/non-polar;
5. (Oxygen) soluble in/can diffuse across (lipid) bilayer;
Blood leaving the kidney eventually returns to the kidney.
Describe the pattern of blood circulation in a mammal that causes blood to
return to the kidney. (6 marks) [Unit 2, June 16]
1. (blood flows from kidney along) renal vein to vena cava;
2. (along) vena cava to RIGHT atrium/side of heart;
3. (along) pulmonary artery to lungs;
4. (along) capillaries to pulmonary vein;
5. (along) pulmonary vein to RIGHT atrium/side of heart;
6. (along) aorta to renal artery (to kidney);
7. Blood may pass through several complete circuits before returning to
kidney;
There are nine subspecies of giraffe. These subspecies evolved when
, Explain how different subspecies of giraffe may have evolved from a
common ancestor. Use information from the passage in your answer. (5
marks) [Unit 4, June 16]
1. No interbreeding / gene pools are separate / geographic(al) isolation;
2. Mutation linked to (different) markings/colours;
3. Selection/survival linked to (different) markings/colours;
4. Adapted organisms breed / differential reproductive success
5. Change/increase in allele frequency/frequencies;
Crops use light energy to produce photosynthetic products.
Describe how crop plants use light energy during the light-dependent
reaction. (5 marks) [Unit 4, June 16]
1. Excites electrons / electrons removed (from chlorophyll);
2. Electrons move along carriers/electron transfer chain releasing energy;
3. Energy use to join AFP and Pi to form ATP;
4. Photolysis of water produces protons, electrons and oxygen;
5. NADP reduced by electrons / electrons and protons / hydrogen;
Describe the advantages and disadvantages of using chemical pesticides
to control pests of crops. (5 marks) [Unit 4, June 16]
(Advantages)
1. Acts quickly;
2. Can apply to a particular area;
3. Kills all/most/wide variety of pests;
(Disadvantages)
4. Needs to be re-applied;
5. Not specific;
6. Pests can develop resistance;
7. (Bio)accumulation;
After harvesting, the remains of crop plants are often ploughed into the soil.
Explain how microorganisms in the soil produce a source of nitrates from
these remains. (5 marks) [Unit 4, June 16]
1. Protein/amino acids/DNA into ammonium compounds / ammonia;
2. By saprobionts;
3. Ammonium/ammonia into nitrite;
4. Nitrite into nitrate;
5. By nitrifiying bacteria/microorganisms;
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller AnswersCOM. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $11.49. You're not tied to anything after your purchase.
