EDEXCEL A-LEVEL BIOLOGY PAPER 1 QUESTIONS AND ANSWERS 2025
How can a paternity test show that an alleged father is not the biological father? - (ANSWER)child has
micro-satellites that are not from mother or alleged father, so must be from a different person
(biological father)
What are short tandem repeats? - (ANSWER)micro-satellite regions commonly used in DNA
identification
In Southern blotting, what is hybridisation? - (ANSWER)gene probes bind with complementary strands
What is a gene probe? - (ANSWER)short DNA sequences, complementary to specific sequences
What may be placed over a gel in Southern blotting? - (ANSWER)nylon filter or nitrocellulose paper
Hoe are DNA fragments extracted using Southern blotting? - (ANSWER)alkaline buffer, absorbent filter
placed over it
What dye is commonly used in gel electrophoresis? - (ANSWER)ethidium bromide
What is the purpose of the second step of PCR? - (ANSWER)primers bind to DNA strands
What may be reasons somebody can't be vaccinated and so relies on herd immunity? -
(ANSWER)allergies, immune system diseases
What is neutralisation in the immune response? - (ANSWER)antibodies neutralise the effects of toxins
What happens when a macrophage engulfs a pathogen? - (ANSWER)combines pathogen antigens with
MHC proteins
What substance is broken down in cellular respiration? - (ANSWER)respiratory susbstrate
,EDEXCEL A-LEVEL BIOLOGY PAPER 1 QUESTIONS AND ANSWERS 2025
What is the main respiratory substrate? - (ANSWER)glucose
What catalyses the hydrolysis of ATP? - (ANSWER)ATPase
What is produced by the hydrolysis of ATP? - (ANSWER)ADP + phosphate
What causes rigor mortis? - (ANSWER)ATP production stops
What are the two main phases of respiration? - (ANSWER)glycolysis, Krebs cycle
What part of respiration requires oxygen? - (ANSWER)Krebs cycle
Where does glycolysis take place? - (ANSWER)cytoplasm
Where does the link reaction, electron transport chain, and Krebs cycle happen? -
(ANSWER)mitochondria
What are stalked particles of a mitochondrion? - (ANSWER)site of ATP production on cristae
What cell types have large amounts of mitochondria, and why? - (ANSWER)active cells, high energy
demand
What is a molecule that receives hydrogen to become reduced? - (ANSWER)hydrogen acceptor
What is NAD? - (ANSWER)conenzyme hydrogen acceptor in respiration
What is NADH? - (ANSWER)reduced NAD
,EDEXCEL A-LEVEL BIOLOGY PAPER 1 QUESTIONS AND ANSWERS 2025
What is NAD+? - (ANSWER)oxidised NAD
Name two hydrogen acceptors in respiration and their reduced molecules - (ANSWER)NAD -> NADH,
FAD -> FADH2
How can respiration of a whole organism be measured? - (ANSWER)respirometer
What is used to absorb the carbon dioxide produced by organisms when respiration is measured? -
(ANSWER)soda lime
What are three ways to investigate respiration in cell fragments? - (ANSWER)centrifuge to separate
mitochondria, electron microscope, separate stalked particles
How do mitochondria separated from their cells prove respiration when supplied with oxygen and
glucose? - (ANSWER)ATP is produced
What information can an electron microscope give about mitochondria? - (ANSWER)stalked particles
provide a large SA
What is produced by glycolysis? - (ANSWER)pyruvate
What are the four main stages of glycolysis? - (ANSWER)6C glucose -> 6C phosphorylated sugar -> 2x3C
sugar -> 2x3C pyruvate
What happens between 6C glucose -> 6C phosphorylated sugar? - (ANSWER)ATP -> ADP
What happens between 2x3C sugar -> 2x3C pyruvate? - (ANSWER)NAD -> NADH, ADP -> ATP
What happens when there is insufficient oxygen for pyruvate to enter the mitochondria? -
(ANSWER)anaerobic respiration
, EDEXCEL A-LEVEL BIOLOGY PAPER 1 QUESTIONS AND ANSWERS 2025
In anaerobic respiration, what do plants convert pyruvate into? - (ANSWER)ethanol
In anaerobic respiration, what do animals convert pyruvate into? - (ANSWER)lactic acid
Where does anaerobic respiration take place? - (ANSWER)cytoplasm
What does lactic acid dissociate into? - (ANSWER)lactate and H+
How many molecules of ATP are produced per glucose in anaerobic respiration? - (ANSWER)2
How many molecules of ATP are produced per glucose in aerobic respiration? - (ANSWER)8
Why does breathing remain fast after exercise stops? - (ANSWER)oxygen needed to oxidise lactate into
pyruvate
What is the equation for aerobic respiration? - (ANSWER)glucose + oxygen -> carbon dioxide + water +
ATP
What is the equation for anaerobic respiration in animals? - (ANSWER)glucose -> lactic acid + ATP
What is the equation for anaerobic respiration in plants and fungi? - (ANSWER)glucose -> ethanol +
carbon dioxide + ATP
An extract from yeast can still undergo what process? - (ANSWER)converting glucose into ethanol
What is the process of respiration? - (ANSWER)glycolysis, link reaction, Krebs cycle, ETC
How can a paternity test show that an alleged father is not the biological father? - (ANSWER)child has
micro-satellites that are not from mother or alleged father, so must be from a different person
(biological father)
What are short tandem repeats? - (ANSWER)micro-satellite regions commonly used in DNA
identification
In Southern blotting, what is hybridisation? - (ANSWER)gene probes bind with complementary strands
What is a gene probe? - (ANSWER)short DNA sequences, complementary to specific sequences
What may be placed over a gel in Southern blotting? - (ANSWER)nylon filter or nitrocellulose paper
Hoe are DNA fragments extracted using Southern blotting? - (ANSWER)alkaline buffer, absorbent filter
placed over it
What dye is commonly used in gel electrophoresis? - (ANSWER)ethidium bromide
What is the purpose of the second step of PCR? - (ANSWER)primers bind to DNA strands
What may be reasons somebody can't be vaccinated and so relies on herd immunity? -
(ANSWER)allergies, immune system diseases
What is neutralisation in the immune response? - (ANSWER)antibodies neutralise the effects of toxins
What happens when a macrophage engulfs a pathogen? - (ANSWER)combines pathogen antigens with
MHC proteins
What substance is broken down in cellular respiration? - (ANSWER)respiratory susbstrate
,EDEXCEL A-LEVEL BIOLOGY PAPER 1 QUESTIONS AND ANSWERS 2025
What is the main respiratory substrate? - (ANSWER)glucose
What catalyses the hydrolysis of ATP? - (ANSWER)ATPase
What is produced by the hydrolysis of ATP? - (ANSWER)ADP + phosphate
What causes rigor mortis? - (ANSWER)ATP production stops
What are the two main phases of respiration? - (ANSWER)glycolysis, Krebs cycle
What part of respiration requires oxygen? - (ANSWER)Krebs cycle
Where does glycolysis take place? - (ANSWER)cytoplasm
Where does the link reaction, electron transport chain, and Krebs cycle happen? -
(ANSWER)mitochondria
What are stalked particles of a mitochondrion? - (ANSWER)site of ATP production on cristae
What cell types have large amounts of mitochondria, and why? - (ANSWER)active cells, high energy
demand
What is a molecule that receives hydrogen to become reduced? - (ANSWER)hydrogen acceptor
What is NAD? - (ANSWER)conenzyme hydrogen acceptor in respiration
What is NADH? - (ANSWER)reduced NAD
,EDEXCEL A-LEVEL BIOLOGY PAPER 1 QUESTIONS AND ANSWERS 2025
What is NAD+? - (ANSWER)oxidised NAD
Name two hydrogen acceptors in respiration and their reduced molecules - (ANSWER)NAD -> NADH,
FAD -> FADH2
How can respiration of a whole organism be measured? - (ANSWER)respirometer
What is used to absorb the carbon dioxide produced by organisms when respiration is measured? -
(ANSWER)soda lime
What are three ways to investigate respiration in cell fragments? - (ANSWER)centrifuge to separate
mitochondria, electron microscope, separate stalked particles
How do mitochondria separated from their cells prove respiration when supplied with oxygen and
glucose? - (ANSWER)ATP is produced
What information can an electron microscope give about mitochondria? - (ANSWER)stalked particles
provide a large SA
What is produced by glycolysis? - (ANSWER)pyruvate
What are the four main stages of glycolysis? - (ANSWER)6C glucose -> 6C phosphorylated sugar -> 2x3C
sugar -> 2x3C pyruvate
What happens between 6C glucose -> 6C phosphorylated sugar? - (ANSWER)ATP -> ADP
What happens between 2x3C sugar -> 2x3C pyruvate? - (ANSWER)NAD -> NADH, ADP -> ATP
What happens when there is insufficient oxygen for pyruvate to enter the mitochondria? -
(ANSWER)anaerobic respiration
, EDEXCEL A-LEVEL BIOLOGY PAPER 1 QUESTIONS AND ANSWERS 2025
In anaerobic respiration, what do plants convert pyruvate into? - (ANSWER)ethanol
In anaerobic respiration, what do animals convert pyruvate into? - (ANSWER)lactic acid
Where does anaerobic respiration take place? - (ANSWER)cytoplasm
What does lactic acid dissociate into? - (ANSWER)lactate and H+
How many molecules of ATP are produced per glucose in anaerobic respiration? - (ANSWER)2
How many molecules of ATP are produced per glucose in aerobic respiration? - (ANSWER)8
Why does breathing remain fast after exercise stops? - (ANSWER)oxygen needed to oxidise lactate into
pyruvate
What is the equation for aerobic respiration? - (ANSWER)glucose + oxygen -> carbon dioxide + water +
ATP
What is the equation for anaerobic respiration in animals? - (ANSWER)glucose -> lactic acid + ATP
What is the equation for anaerobic respiration in plants and fungi? - (ANSWER)glucose -> ethanol +
carbon dioxide + ATP
An extract from yeast can still undergo what process? - (ANSWER)converting glucose into ethanol
What is the process of respiration? - (ANSWER)glycolysis, link reaction, Krebs cycle, ETC
