Cells require a molecule that directly transfers usable energy for metabolic processes such as active transport and biosynthesis. What molecule performs this role?
ATP
ATP releases energy when its terminal phosphate bond is hydrolysed.
In which part of the cell does the first stage of respiration occur?
Cytoplasm
This stage is independent of oxygen and therefore occurs outside mitochondria.
The first stage of respiration that splits a six-carbon sugar into two three-carbon molecules is called what?
Glycolysis
Occurs in the cytoplasm and does not require oxygen.
During the initial stage of glycolysis, what type of reaction adds phosphate groups to glucose using ATP?
Phosphorylation
Two ATP molecules are used to activate glucose at the start of glycolysis.
What three-carbon molecule is produced at the end of glycolysis?
Pyruvate
Two molecules of this compound are produced from one glucose molecule.
Which reduced coenzyme is produced when triose phosphate is oxidised during glycolysis?
Reduced NAD
This molecule later donates electrons to the electron transport chain in aerobic respiration.
True or False:
Glycolysis requires oxygen in order to proceed.
False
Glycolysis is an anaerobic process and occurs whether oxygen is present or not.
Fill in the blank:
In anaerobic respiration in animal cells, pyruvate is converted to ______.
Lactate
This reaction regenerates oxidised NAD so glycolysis can continue.
Fill in the blanks:
In anaerobic respiration in yeast, pyruvate is converted to ethanol and ______ ______.
Carbon dioxide
This process is commonly known as alcoholic fermentation.
When oxygen is available, pyruvate must enter which part of the mitochondrion before further reactions occur?
Mitochondrial matrix
Pyruvate is transported into the matrix by active transport.
In the link reaction connecting glycolysis to the Krebs cycle, pyruvate is converted into acetate and which reduced coenzyme is produced?
Reduced NAD
This oxidation step releases carbon dioxide.
What molecule is formed when acetate combines with coenzyme A in the link reaction?
Acetyl coenzyme A
This compound enters the Krebs cycle.
The cyclic pathway that generates reduced coenzymes, ATP, and carbon dioxide in the mitochondrial matrix is called what?
Krebs cycle
Also known as the citric acid cycle or tricarboxylic acid cycle.
What process produces ATP when electrons move down the electron transport chain and drive proton movement across the inner mitochondrial membrane?
Oxidative phosphorylation
This process involves chemiosmosis and ATP synthase.
What enzyme embedded in the inner mitochondrial membrane catalyses the formation of ATP using a proton gradient?
ATP synthase
Protons flow through this enzyme down their electrochemical gradient.
True or False:
The Krebs cycle produces ATP directly by substrate-level phosphorylation.
True
A small amount of ATP is formed directly in the cycle.
Besides carbohydrates, which two types of biological molecules can be broken down and enter respiratory pathways?
- Lipids
- Proteins
Their breakdown products feed into the Krebs cycle.
-
1: Biological Molecules138
-
1: Enzymes & Digestion16
-
1: Cell Structure52
-
1: Cell Division20
-
1: Membranes & Transport20
-
2: Exchange & Transport Systems76
-
2: Plant Transport20
-
2: Immunology36
-
3: DNA & Protein Synthesis27
-
3: Genetic Diversity14
-
3: Biodiversity & Classification32
-
3: Investigating Diversity12
-
4: Evolution42
-
4: Populations & Ecosystems24
-
4: Energy & Nutrient Cycles35
-
5: Photosynthesis23
-
5: Respiration17
-
5: ATP & Energy Transfer11
-
6: Homeostasis57
-
6: Nervous Coordination53
-
6: Stimuli & Response62
-
6: Muscles14
-
7: Inheritance12
-
7: Populations (Hardy–Weinberg)15
-
8: Gene Mutations & Expression58
-
8: Gene Technologies46
-
8: Disease24
