Respiration, AQA, Resource List, Exam Questions Tom Whitburn Respiration, AQA, Resource List, Exam Questions Tom Whitburn

Respiration - Test your understanding, tips, resources and a quiz

Oxygen is the final electron acceptor. It oxidises the final carrier in the ETC on the inner mitochondrial membrane and is reduced to water.

Hydrogen ions flow from the inter membrane space into the matrix via ATP synthase, this electrochemical gradient phosphorylates ADP.

Hydrogen ions are pumped from the matrix into the inter membrane space, using the energy from the electrons flowing along the ETC. The electrons come from the oxidation of food, transferred by coenzymes NAD and FAD.

Glycolysis occurs in the cytoplasm. Link and Krebs in the matrix. Link and Krebs produce carbon dioxide by the removal of a carboxyl group.

Fermentation is just glycolysis with a different way of regenerating NAD (from NADH) by the reduction of pyruvate (or ethanal).

Substrate level phosphorylation is the direct addition of phosphate to ADP, occurs in glycolysis (4 ATP) and Krebs (once per turn), chemiosmosis is H ions flowing through ATP synthase.

Cristae give a larger surface area for oxidative phosphorylation

Read More
Photosynthesis, AQA, Resource List, Exam Questions Tom Whitburn Photosynthesis, AQA, Resource List, Exam Questions Tom Whitburn

Photosynthesis Tips - Notes, videos, powerpoints and a pack of long questions

Powerpoints and notes, a pack of long data analysis exam questions and a test on photosynthesis

Tips for Photosynthesis

LDR - occurs on the thylakoid membranes. Limiting factor is light intensity

  • Phosphorylates ADP (through chemiosmosis) - creates the Hydrogen ion gradient by the flow of electrons along the ETC in the thylakoid membrane. The flow of electrons is driven by the capturing of light by a range of different pigments which channel the energy to a chl a molecule at the reaction centre of the photosystem - which then loses an electron.

  • Reduces NADP with an electron from splitting water (photolysis) at PSII.

Light Independent Reaction (reduction of carbon dioxide) - occurs in the stroma (the cytoplasm of the chloroplast).

  • Limited by speed and quantity of RUBISCO enzyme (kinetic energy - temperature) and substrate concentration (Carbon dioxide)

  • Needs the products of the LDR - ATP and NADPH

  • NADPH and ATP are used to regenerate RUBP

  • Each time the Calvin cycle turns, a single Carbon is reduced. 3 turns - one extra Triose Phosphate. 6 turns - 2 extra TP = 1 extra glucose.

  • TP is the source of all of the carbon in all plants (and hence in all heterotrophes) - Amino acids, DNA, RNA, phospholipids etc

Read More
Exam Questions Tom Whitburn Exam Questions Tom Whitburn

A-level Biology: Practical and Experimental Design - Top Tips and Question Pack

Top Tips !

  • Never write "amount" you mean mass, volume or concentration. 
  • Refer to "a control experiment" or "a variable that I will control (and then name the value and method of control)" but never to "a control variable"
  • Independent variable is what you change.
  • Dependent variable is what you actually measure in the experiment (not rate).
  • Organisms vary from each other unless they are clones !
  • When you suggest improvements think about improving the method rather than the equipment (e.g. control a variable that wasn't previously)

If you use then like and share

Read More
Heart, OCR, Exam Questions Tom Whitburn Heart, OCR, Exam Questions Tom Whitburn

Cardiac Cycle of the Heart and Transport in Animals Questions for A-level Biology - with video and PowerPoint to recap the theory

How to approach the Cardiac Cycle and answer A-level Biology Questions on mass transport in animals. Lots of past paper questions. Cardiac Cycle of the Heart and Transport in Animals Questions for A-level Biology - with video and PowerPoint to recap the theory.

If you use then please like and share

Read More