Pearson Edexcel GCSE Combined Science · B2

Cells and control

50 revision questions with answers for B2 Cells and control in Pearson Edexcel GCSE Combined Science (spec 1SC0). Practise with flashcards, a topic quiz, a random quiz across the course, 5 crosswords, or read every question and answer below. Not official Pearson material.

All 50 questions and answers

Question 1 · Spec B2.1
What is the cell cycle?
Answer:
The sequence of growth, DNA replication, nuclear division and cell division that produces new cells.
Question 2 · Spec B2.1
What happens during interphase?
Answer:
The cell grows, increases sub-cellular structures and replicates its DNA before mitosis.
Question 3 · Spec B2.1
What happens during prophase?
Answer:
Chromosomes condense and become visible; the nuclear envelope breaks down and the spindle forms.
Question 4 · Spec B2.1
What happens during metaphase?
Answer:
Chromosomes line up at the cell's equator and attach to spindle fibres.
Question 5 · Spec B2.1
What happens during anaphase?
Answer:
Sister chromatids separate and are pulled towards opposite poles.
Question 6 · Spec B2.1
What happens during telophase?
Answer:
Chromosomes reach opposite poles and new nuclear envelopes form around each set.
Question 7 · Spec B2.1
What is cytokinesis?
Answer:
Division of the cytoplasm and cell membrane to form separate daughter cells.
Question 8 · Spec B2.1
Put the mitosis stages in order.
Answer:
Prophase, metaphase, anaphase, telophase; DNA replication occurs beforehand in interphase.
Question 9 · Spec B2.1
A cell image shows chromosomes along its equator. Which stage is shown?
Answer:
Metaphase.
Question 10 · Spec B2.1
A cell image shows chromatids moving to opposite poles. Which stage is shown?
Answer:
Anaphase.
Question 11 · Spec B2.2
Why is mitosis needed for growth?
Answer:
It increases the number of cells while maintaining their genetic information.
Question 12 · Spec B2.2
How does mitosis help repair tissues?
Answer:
It produces replacement cells with the same genetic information as the original body cells.
Question 13 · Spec B2.2
How does mitosis enable asexual reproduction?
Answer:
One parent produces genetically identical offspring without gamete fusion.
Question 14 · Spec B2.3
Describe the two cells produced by mitosis.
Answer:
Two genetically identical diploid daughter cells with the same chromosome sets as the parent cell.
Question 15 · Spec B2.3
A diploid parent has 46 chromosomes. How many does each mitotic daughter receive?
Answer:
46 chromosomes, preserving the diploid chromosome number.
Question 16 · Spec B2.3
Why must DNA replicate before mitosis?
Answer:
So each daughter cell can receive a complete, identical set of chromosomes.
Question 17 · Spec B2.4
How is cancer related to the cell cycle?
Answer:
Changes in cells cause loss of normal control over cell division, leading to uncontrolled division.
Question 18 · Spec B2.4
Why can repeated uncontrolled mitosis form a tumour?
Answer:
It increases cell numbers in a region, producing an abnormal mass of cells.
Question 19 · Spec B2.5
How do animals grow at the cellular level?
Answer:
By cell division followed by growth and differentiation of cells.
Question 20 · Spec B2.5
How does plant growth differ from animal growth?
Answer:
Plants grow through cell division, cell elongation and differentiation; elongation contributes substantially to increased length.
Question 21 · Spec B2.6
What is cell differentiation?
Answer:
Development of specialised structures that allow a cell to perform a particular function.
Question 22 · Spec B2.6
Why is differentiation important in a multicellular organism?
Answer:
It produces specialised cells that perform different tasks and cooperate within tissues and organs.
Question 23 · Spec B2.7
What does the 50th percentile on a growth chart represent?
Answer:
The median: about half of the reference population is below it and half above it.
Question 24 · Spec B2.7
A child's height is at the 75th percentile. What does that mean?
Answer:
About 75% of children in the reference group have a lower height and about 25% a higher height.
Question 25 · Spec B2.7
Why can change in percentile over time be more informative than one measurement?
Answer:
It shows the growth pattern; a persistent large change may justify further investigation, while one value may reflect normal variation.
Question 26 · Spec B2.8
What is a stem cell?
Answer:
An undifferentiated cell that can divide and develop into specialised cell types.
Question 27 · Spec B2.8
What can embryonic stem cells develop into?
Answer:
Many different specialised body cell types.
Question 28 · Spec B2.8
What is a function of adult bone-marrow stem cells?
Answer:
They divide and differentiate to replace blood cells.
Question 29 · Spec B2.8
What are meristems?
Answer:
Regions of plant tissue containing dividing, undifferentiated cells that supply cells for growth.
Question 30 · Spec B2.8
How does a meristem support continued plant growth?
Answer:
Its cells divide, then daughter cells can elongate and differentiate into needed plant tissues.
Question 31 · Spec B2.9
Give a possible medical benefit of stem cells.
Answer:
They may replace damaged or non-functional cells, helping restore tissue function.
Question 32 · Spec B2.9
Why could transplanted stem cells be rejected?
Answer:
The immune system may recognise cells from another individual as foreign.
Question 33 · Spec B2.9
Why can uncontrolled division be a risk in stem-cell treatments?
Answer:
The transplanted cells may divide excessively and form tumours.
Question 34 · Spec B2.9
Give an ethical concern about embryonic stem-cell use.
Answer:
Some people object to the destruction or use of embryos; views depend on the moral status assigned to embryos.
Question 35 · Spec B2.13
What does a sensory receptor do?
Answer:
It detects a stimulus and initiates a signal in the nervous system.
Question 36 · Spec B2.13
What are the roles of sensory, relay and motor neurones?
Answer:
Sensory neurones carry impulses to the CNS; relay neurones connect within it; motor neurones carry impulses to effectors.
Question 37 · Spec B2.13
What is an axon's function?
Answer:
It carries electrical impulses away from the neurone's cell body.
Question 38 · Spec B2.13
What is a dendron's function in a sensory neurone?
Answer:
It carries an impulse from a receptor towards the cell body.
Question 39 · Spec B2.13
What does a myelin sheath do?
Answer:
It insulates the neurone and increases the speed of impulse transmission.
Question 40 · Spec B2.13
What is a synapse?
Answer:
A small gap between neurones where a chemical neurotransmitter transfers the signal.
Question 41 · Spec B2.13
How is a signal transmitted across a synapse?
Answer:
An impulse triggers neurotransmitter release; it diffuses across the gap and binds receptors, triggering an impulse in the next neurone.
Question 42 · Spec B2.13
Why does a synapse usually transmit in one direction?
Answer:
Neurotransmitter is released from the presynaptic ending and receptors are located on the postsynaptic membrane.
Question 43 · Spec B2.13
How could impulse speed be calculated from data?
Answer:
Speed = distance travelled / transmission time, using consistent distance and time units.
Question 44 · Spec B2.13
An impulse travels 1.2 m in 0.020 s. Calculate speed.
Answer:
Speed = 1.2 / 0.020 = 60 m/s.
Question 45 · Spec B2.14
State the route through a simple spinal reflex arc.
Answer:
Receptor → sensory neurone → relay neurone → motor neurone → effector.
Question 46 · Spec B2.14
Why are reflex actions rapid and automatic?
Answer:
They do not require conscious decision-making, allowing quick protective responses.
Question 47 · Spec B2.14
What is the effector when a hand withdraws from a hot surface?
Answer:
A muscle that contracts to move the hand away.
Question 48 · Spec B2.14
Why does damage to a sensory neurone prevent a normal reflex?
Answer:
The impulse cannot reach the coordinating part of the reflex pathway.
Question 49 · Spec B2.14
Why does damage to a motor neurone prevent the muscle response?
Answer:
The impulse cannot travel from the CNS to the effector.
Question 50 · Spec B2.14
How could a ruler-drop investigation compare reaction times fairly?
Answer:
Use consistent starting positions and release methods, allow practice, repeat trials and compare means for the chosen factor.

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