Track quiz

Here are the nine rules, in the lessons' own words.

Control and Coordination — the nine rules
Idea	The rule
One body, many parts	A body has many parts with different jobs. They must act together, not alone. The nervous system and hormones keep them in step.
The message and the messenger	A neuron is a nerve cell. It carries a signal as electricity, one way, dendrite to nerve ending. At a synapse, it crosses as a chemical to the next cell.
The shortest path	A reflex is a fast, automatic response. Its arc often closes in the spinal cord. The muscle acts without waiting for the thinking part of the brain.
The centre and the cable	The brain and spinal cord are the body's centre. The brain has three parts: forebrain, midbrain and hindbrain. The cerebellum keeps balance. The medulla runs blood pressure, salivation and vomiting.
Messages in the blood	A hormone is a chemical messenger. A gland releases it into the blood. The blood carries it round the body. It acts only on its target cells.
Sugar and feedback	Feedback keeps blood sugar steady. When blood sugar rises, the pancreas makes more insulin. When the sugar falls, it makes less.
Plants bend toward the light	Plants coordinate by chemistry, not nerves. Light makes a growth chemical gather on the shaded side. The shaded side grows more, so the shoot bends toward light.
Other plant hormones	Plants make other hormones too. Gibberellins help stems grow longer. Cytokinins help cells divide. Abscisic acid slows growth.
Fast and slow, side by side	Nerves are usually fast and reach one place. Hormones are usually slower and reach many places, and some last longer. Each fits jobs the other does badly.

A cyclist's eyes see a stray dog. The legs brake two seconds late. What failed?

The legs are naturally slower than the eyes
Coordination matters in a reflex, not in ordinary riding
The message reached the legs too late to help

A signal moves down a neuron, then crosses to the next cell. Which is correct?

Electrical inside the neuron, chemical at the synapse
It is chemical inside the neuron and electrical at the synapse
It stays electrical the whole way

Order these reflex-arc stations, from receptor to effector.

Receptor, motor neuron, relay neuron, sensory neuron, effector
Receptor, sensory neuron, relay neuron, motor neuron, effector
Relay neuron, receptor, sensory neuron, effector, motor neuron

A person balances on one foot without falling. Which brain part is most responsible?

The forebrain, which does the thinking
The cerebellum, which keeps balance and posture
The medulla, which runs blood pressure and more

A person's neck gland is short of iodine. Which hormone falls short, and what can follow?

Thyroxin falls short; the neck swells, called goitre
Insulin falls short; blood sugar cannot be controlled
Adrenaline falls short; the heart cannot race

After a meal, blood sugar rises. What does the pancreas do next?

It makes less insulin
It stops making any hormone
It makes more insulin

A seedling's pot is turned. Light now comes from the other side. What happens next?

The shoot stays bent the old way. The chemical cannot move to the new side
The shoot straightens out. Growth stops
The chemical moves to the new shaded side. The shoot bends again

A gardener wants a young plant to grow a longer stem. Which hormone helps most?

Abscisic acid, which slows growth
Gibberellins, which help stems grow longer
Cytokinins, which help cells divide

A hand touches a sharp pin and pulls back at once. Which carrier explains this, and why?

The hormone, since it reaches every part at once
The nerve, since it is fast and reaches one place
Both carriers, since either could have caused the same pull

Chapter 6 of your Class 10 book, Science — Control and Coordination. Read it now, and match its figures to your own.

One door on: Chapter 7 asks where new bodies come from. It is called How do Organisms Reproduce?

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