Plant and Animal Responses | OCR A-Level Biology A (H420)

Plant and Animal Responses

80 questions
7 subtopics
Module 5: Communication, homeostasis and energy
Component 01 and Component 03

Plant and animal responses is the fifth section of Module 5.

It covers tropisms and the hormones behind them and their commercial uses, the organisation of the nervous system, the reflex arc, fight or flight and the control of heart rate, and how a muscle contracts.

Sample questions from Plant and Animal Responses

Answer each one closed book first, then open the answer.

Tropisms and plant responses to stress and herbivory

Distinguish between positive and negative tropism.

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Positive tropism is growth towards a stimulus; negative tropism is growth away from a stimulus.
Tropisms and plant responses to stress and herbivory

How can pheromones released by plants in response to herbivory benefit the plant?

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They can attract predators of the herbivores or warn neighbouring plants of the threat.
Plant hormones and their commercial uses

Define apical dominance.

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The phenomenon where the main central stem grows more strongly than lateral branches, inhibiting their growth.
Plant hormones and their commercial uses

What is serial dilution and why is it used in plant hormone investigations?

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Serial dilution is a technique used to prepare a range of concentrations of plant hormones for investigating their effects on growth.
The nervous system and the brain

What does the somatic nervous system control?

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Voluntary movements by innervating skeletal muscles.
The nervous system and the brain

Which autonomic functions does the medulla oblongata control?

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Heart rate, breathing rate, and blood pressure.
Reflex actions and the knee jerk reflex

What type of receptor detects the stretch in the knee jerk reflex?

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A muscle spindle.
Reflex actions and the knee jerk reflex

What does the motor neurone stimulate in the knee jerk reflex?

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Contraction of the quadriceps muscle.

The 7 subtopics

One subtopic is one session. Work down the list.

Subtopic	What it covers	Questions
Tropisms and plant responses to stress and herbivory	Positive and negative phototropism and geotropism, the alkaloids, pheromones and touch responses that deter herbivores, and how tropisms are investigated.	11
Plant hormones and their commercial uses	Auxins and apical dominance, gibberellins in germination and stem elongation, abscisic acid in abscission and stomatal closure, and ethylene, rooting powders and weed killers.	16
The nervous system and the brain	The central and peripheral nervous systems and the somatic and autonomic divisions, and the cerebrum, cerebellum, medulla oblongata, hypothalamus and pituitary gland.	10
Reflex actions and the knee jerk reflex	What makes an action a reflex and why reflexes have survival value, and the stimulus, receptor, neurones and response of the monosynaptic knee jerk.	8
Fight or flight and the control of heart rate	The adrenal medulla and the physiological effects of adrenaline, the second messenger cascade through cyclic AMP, and sympathetic and parasympathetic control of heart rate.	12
The structure of skeletal muscle	Skeletal, smooth and cardiac muscle compared, myofibrils and the proteins of the thick and thin filaments, and the I band, A band, H zone and Z line.	10
The neuromuscular junction and the sliding filament model	How an impulse crosses to the sarcolemma, the calcium ions that expose the binding sites, cross-bridge formation and the power stroke, and the ATP and creatine phosphate that supply it.	13

Plant and Animal Responses is 80 of the 1,833 questions in the guide.Get the guide, £8

How the guide is worked

Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.

Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.

Read the full method, the return schedule and the research behind it.