OCR A+Level Biology Paper 1 (Priority Topics) .pdf OCR A+Level Biology Paper 1 (Priority Topics) .pdf OCR A+Level Biology Paper 1 (Priority Topics) .pdf
OCR A+Level Biology Paper 1
(Priority Topics)
Auxin is a plant hormone produced in the shoot tip. Auxin causes cell elongation and
travels down the stem from the tip. Auxin is destroyed by sunlight. Explain how this
leads to positive phototropism in the plant. - ANS-Auxin is broken down on the sunny
side of the plant. Cells on the shaded side will elongate due to auxin, causing curvature
of the stem so that the plant grows towards the light.
Ivy plants often use walls or other plants as a support when growing. State the type of
tropism being used. - ANS-Thigmotropism
Roots grow towards the centre of gravity. State the type of tropism this demonstrates. -
ANS-Positive geotropism
A gardener decides that they would like a plant that grows as wide as possible. Suggest
and explain how they could cut the plant in order to achieve this shape. - ANS-The
gardener would need to cut off the shoot tip containing the apical meristem. This would
allow side branches to grow from lateral buds, and so form a plant with side branches.
State the role of gibberellin. - ANS-It is a growth regulator, causing stem elongation
State the role of cytokinin - ANS-It promotes lateral bud growth
State two commercial uses of gibberellins with reference to plants. - ANS-They can be
used to enhance seed germination in growing malt for beer, and delay senescence of
citrus fruits, making them available for longer in shops.
State two commercial uses of auxins. - ANS-They can be used in rooting powder to
grow roots in young plant cuttings, and can be used as a herbicide to kill weeds.
State the different neurones located in the central and peripheral nervous systems. -
ANS-The PNS is made up of sensory and motor neurones, whereas the CNS is mostly
made up of relay neurones.
State the role of the sympathetic nervous system. - ANS-Activating the fight-or-flight
OCR A+Level Biology Paper 1 (Priority Topics) .pdf OCR A+Level Biology Paper 1 (Priority Topics) .pdf OCR A+Level Biology Paper 1 (Priority Topics) .pdf
, OCR A+Level Biology Paper 1 (Priority Topics) .pdf OCR A+Level Biology Paper 1 (Priority Topics) .pdf OCR A+Level Biology Paper 1 (Priority Topics) .pdf
response, preparing the body for activity and stimulating effectors
State the function of the medulla oblongata. - ANS-Controlling the
involuntary/autonomic functions/responses, such as heart rate.
State one function of the pituitary gland. - ANS-Storing and releasing hormones that
regulate homeostatic mechanisms in the body, such as thermoregulation or
osmoregulation.
State two processes controlled by the hypothalamus. - ANS-Monitoring the composition
of the blood plasma and hormone production.
Describe what is meant by a 'second messenger molecule'. - ANS-A signalling molecule
inside a cell that is activated by a hormone (first messenger) binding to the outside of
the cell, which stimulates a change in the activity of the cell.
Describe the basic structure of mammalian skeletal muscle. - ANS-It is made up of
many smaller strands or fibres, called myofibrils. Myofibrils are made up of many
repeating units called sarcomeres.
State the name of the neurotransmitter released at the neuromuscular junction. -
ANS-Acetylcholine
Describe how actin and myosin are arranged in resting muscle. - ANS-Myosin and actin
are not interlocked. Wide I-bands are present and there are visible H-zones.
Giving an example, explain why plants need to carry out the process of respiration. -
ANS-Respiration is used to synthesise molecules of ATP, which is then used for
energy-requiring processes around the plant
State precisely where the link reaction takes place in the cell. - ANS-The mitochondrial
matrix
Describe where pyruvate, which is produced in glycolysis, would move to be used in the
link reaction. - ANS-Across both the outer and inner mitochondrial membranes into the
mitochondrial matrix
Explain the term decarboxylation. - ANS-Removal of a carbon dioxide/carboxyl group
Describe what is meant by a respiratory substrate - ANS-An organic substance that can
OCR A+Level Biology Paper 1 (Priority Topics) .pdf OCR A+Level Biology Paper 1 (Priority Topics) .pdf OCR A+Level Biology Paper 1 (Priority Topics) .pdf
OCR A+Level Biology Paper 1
(Priority Topics)
Auxin is a plant hormone produced in the shoot tip. Auxin causes cell elongation and
travels down the stem from the tip. Auxin is destroyed by sunlight. Explain how this
leads to positive phototropism in the plant. - ANS-Auxin is broken down on the sunny
side of the plant. Cells on the shaded side will elongate due to auxin, causing curvature
of the stem so that the plant grows towards the light.
Ivy plants often use walls or other plants as a support when growing. State the type of
tropism being used. - ANS-Thigmotropism
Roots grow towards the centre of gravity. State the type of tropism this demonstrates. -
ANS-Positive geotropism
A gardener decides that they would like a plant that grows as wide as possible. Suggest
and explain how they could cut the plant in order to achieve this shape. - ANS-The
gardener would need to cut off the shoot tip containing the apical meristem. This would
allow side branches to grow from lateral buds, and so form a plant with side branches.
State the role of gibberellin. - ANS-It is a growth regulator, causing stem elongation
State the role of cytokinin - ANS-It promotes lateral bud growth
State two commercial uses of gibberellins with reference to plants. - ANS-They can be
used to enhance seed germination in growing malt for beer, and delay senescence of
citrus fruits, making them available for longer in shops.
State two commercial uses of auxins. - ANS-They can be used in rooting powder to
grow roots in young plant cuttings, and can be used as a herbicide to kill weeds.
State the different neurones located in the central and peripheral nervous systems. -
ANS-The PNS is made up of sensory and motor neurones, whereas the CNS is mostly
made up of relay neurones.
State the role of the sympathetic nervous system. - ANS-Activating the fight-or-flight
OCR A+Level Biology Paper 1 (Priority Topics) .pdf OCR A+Level Biology Paper 1 (Priority Topics) .pdf OCR A+Level Biology Paper 1 (Priority Topics) .pdf
, OCR A+Level Biology Paper 1 (Priority Topics) .pdf OCR A+Level Biology Paper 1 (Priority Topics) .pdf OCR A+Level Biology Paper 1 (Priority Topics) .pdf
response, preparing the body for activity and stimulating effectors
State the function of the medulla oblongata. - ANS-Controlling the
involuntary/autonomic functions/responses, such as heart rate.
State one function of the pituitary gland. - ANS-Storing and releasing hormones that
regulate homeostatic mechanisms in the body, such as thermoregulation or
osmoregulation.
State two processes controlled by the hypothalamus. - ANS-Monitoring the composition
of the blood plasma and hormone production.
Describe what is meant by a 'second messenger molecule'. - ANS-A signalling molecule
inside a cell that is activated by a hormone (first messenger) binding to the outside of
the cell, which stimulates a change in the activity of the cell.
Describe the basic structure of mammalian skeletal muscle. - ANS-It is made up of
many smaller strands or fibres, called myofibrils. Myofibrils are made up of many
repeating units called sarcomeres.
State the name of the neurotransmitter released at the neuromuscular junction. -
ANS-Acetylcholine
Describe how actin and myosin are arranged in resting muscle. - ANS-Myosin and actin
are not interlocked. Wide I-bands are present and there are visible H-zones.
Giving an example, explain why plants need to carry out the process of respiration. -
ANS-Respiration is used to synthesise molecules of ATP, which is then used for
energy-requiring processes around the plant
State precisely where the link reaction takes place in the cell. - ANS-The mitochondrial
matrix
Describe where pyruvate, which is produced in glycolysis, would move to be used in the
link reaction. - ANS-Across both the outer and inner mitochondrial membranes into the
mitochondrial matrix
Explain the term decarboxylation. - ANS-Removal of a carbon dioxide/carboxyl group
Describe what is meant by a respiratory substrate - ANS-An organic substance that can
OCR A+Level Biology Paper 1 (Priority Topics) .pdf OCR A+Level Biology Paper 1 (Priority Topics) .pdf OCR A+Level Biology Paper 1 (Priority Topics) .pdf
