Biology - Detecting our Environment (AQA)
Evolution has equipped us with various senses with which to detect our environment.

Biology - Detecting our Environment (AQA)

How organisms use nerves and hormones is one of the topics covered in GCSE Science. This is the first of five quizzes on the subject and it looks at the senses we, and other animals, use for detecting our environment. This refers not only to the five senses of sight, hearing, taste, touch and smell, but also to other senses such as balance.

All animals, humans included, need to have a system that can be used for detecting their surroundings or environment. Without such a system it would not be possible to move around, find food, escape danger and so on. Evolution has equipped animals with several senses, including the obvious five of sight, hearing, touch, taste and smell. These detect the environment and send messages to the brain. The brain then interprets these signals so that animals can make sense of the world around them.

Messages are carried by the nervous system. This enables animals to react to or interact with their surroundings and to coordinate their behaviour according to the exact situation. The nervous system is made up of long thin nerve cells (neurons) that join together in long strings to make nerves, but with a little gap between them. Inside the nerve cell messages are carried along as electrical signals, but between nerve cells the messages are usually transmitted across the gap by chemcals.

When we humans are deprived of one or more of our senses, it is still possible for us to function almost normally. We can find other ways of detecting our surroundings. For example, people who have lost their sight can learn to get around using a stick or with the help of a guide dog and people who have lost their sense of hearing learn to communicate in different ways.

Sometimes, when people have an accident and break their back they lose the use of their legs. Why does this happen?
The part of the brain that controls their legs is damaged
They lose the blood supply to their legs
The muscles at the top of the legs become disconnected from the backbone
The spinal cord is severed and signals from the brain can't reach their legs
When the spinal cord is severed, the nerves are snapped so no messages can be sent between the brain and the legs. Not everyone who breaks their back loses the use of their legs
In which section of the brain are voluntary muscle messages processed?
Frontal lobe
Voluntary muscles are the ones that you can control e.g. calf muscle or biceps. The medulla deals with autonomic, involuntary functions such as breathing and heart rate. The frontal lobe deals with many of your thinking skills and the hypothalamus deals with the endocrine system (glands and hormones)
Sense organs have receptors. Receptors detect changes in the environment. Which word describes one of these changes in the environment that is detected?
An effector
An affector
A neuron
A stimulus
It is called a stimulus because it stimulates a receptor cell
Your ears contain receptors sensitive to sound. But what other receptors can be found there?
All three of the above
The inner ear contains receptors that can detect changes in position enabling you to keep your balance
Which of the following are effectors?
Eyes and ears
Bones and blood
Muscles and glands
An effector is an organ that makes something happen. Muscles make parts of the body move, glands produce hormones which carry messages to organs to make them do something e.g. the adrenal gland produces the hormone adrenalin which prepares the body to fight or run away
Which of the following correctly describes the order of the nerve pathways?
Receptor, motor neuron, CNS, sensory neuron, effector
Effector, sensory neuron, motor neuron, CNS, receptor
Receptor, sensory neuron, CNS, motor neuron, effector
Receptor, CNS, sensory neuron, motor neuron, effector
A receptor is always connected to a sensory neuron. An effector is always connected to a motor neuron
Which two human sense organs have receptors specifically sensitive to chemicals?
Ears and eyes
Eyes and nose
Nose and tongue
Eyes and skin
Smells and flavours are caused by chemicals
Nerve cells of the nervous system that are responsible for converting external stimuli from the organism's environment into electrical impulses that can be transmitted to the brain are called what?
Sensory neurons
Motor neurons
Relay neurons
Sensory neurons are connected to the receptor cells
Which two organs comprise the central nervous system?
Brain and spinal cord
Brain and eyes
Eyes and spinal cord
Skin and bones
Nerves from the spinal column are connected to almost all parts of the body
A group of students did an experiment about taste. They were given salt, sugar, coffee, vinegar and lemon solutions to taste through a straw but they were blindfolded and had to hold their nose firmly closed. They had difficulty identifying the five flavours. Why?
Sight is important for taste
They weren't allowed to touch the containers with the solutions in
The straw takes away the taste
Identifying a flavour requires both smell and taste
Taste receptors are specialised cells in the taste buds. They can only detect sweetness, sourness, saltiness, bitterness, and umami. Without the sense of smell, you can only guess at a flavour
Author:  Kev Woodward

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