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Unit notes and practice questions

Grade 12 Biology unit 5: Human Body System

Everything here is for unit 5 of the Grade 12 Biology textbook: what the chapter covers, the short notes, practice questions with their answers, and the lesson video where one exists.

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2
Cards
10
Practice questions on unit 5
236–332
The textbook pages for unit 5

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The Temari lesson on unit 5

A short video lesson on this chapter, made by Temari. It loads only when you press play.

How ADH keeps your water balance · 4 min · 2 past exam questions worked through

Parts of the lesson

Tap a part to play the lesson from there.

What unit 5 covers

  1. 1.The nervous system
  2. 2.Sense organs
  3. 3.Homeostasis in the human body

Short notes for unit 5

The cards filed under this chapter on the Grade 12 Biology page. Open one at a time.

Brain RegionMajor Functions
CerebrumInterpreting senses, speech, reasoning, emotions, learning, and fine motor control
ThalamusRelay station for sensory tracts passing to the cerebrum
HypothalamusHomeostatic control of thirst, appetite, body temperature, and endocrine regulation
BrainstemRelay station with crossing nerve tracts and reflex centers for sight, hearing, and touch

When you use it

Use this to recall the primary roles of different brain divisions in sensory processing, integration, and homeostasis.

Watch out

Nerve tracts cross in the brainstem, meaning the left hemisphere controls the right side of the body and vice versa.

Drafted from Grade 12 Biology, pages 236-332, then checked twice before it went up

Meningeal LayerPositionKey Characteristics
Dura materOutermostTough, fibrous double layer, outer periosteal layer absent in spinal cord
Arachnoid materMiddleDelicate serous membrane, subarachnoid space beneath contains CSF
Pia materInnermostDelicate vascular layer clinging tightly to the surface of the brain

When you use it

Use this when identifying the three protective membrane layers covering the brain and spinal cord from outermost to innermost.

Watch out

The periosteal layer of the dura mater is present in the skull but is absent around the spinal cord.

Drafted from Grade 12 Biology, pages 236-332, then checked twice before it went up

Practice questions on unit 5

10 multiple-choice questions written against this chapter, each with its answer and the reason. Try one before you open the answer.

Question 1

Which two parts make up the central nervous system (CNS)?

  1. A.The brain and the spinal cord
  2. B.The brain and the nerves
  3. C.The spinal cord and the nerves
  4. D.The cranium and the vertebral column
Show the answer and why

Answer: A The brain and the spinal cord

Why

The CNS is made up of the brain and the spinal cord. The nerves that branch out from the brain and spinal cord belong to the peripheral nervous system (PNS), so option B and option C are wrong. The cranium and vertebral column are bony structures that protect the CNS, not parts of the CNS itself.

Question 2

Which of the three meninges lies closest to the bone of the skull?

  1. A.Arachnoid mater
  2. B.Pia mater
  3. C.Dura mater
  4. D.Subarachnoid space
Show the answer and why

Answer: C Dura mater

Why

The dura mater is the layer that lies closest to the bone of the skull. It is a double layer of tough, fibrous connective tissue. The subarachnoid space is a space, not one of the three meninges.

Question 3

The brain floats in a special cushioning fluid. What is this fluid called?

  1. A.Aqueous humour
  2. B.Vitreous humour
  3. C.Cerebrospinal fluid (CSF)
  4. D.Synovial fluid
Show the answer and why

Answer: C Cerebrospinal fluid (CSF)

Why

The brain floats in cerebrospinal fluid (CSF). It is a thin fluid similar to plasma. Aqueous humour and vitreous humour are fluids found in the eye, not around the brain.

Question 4

Which part is the largest portion of the brain in humans?

  1. A.Cerebellum
  2. B.Medulla oblongata
  3. C.Cerebrum
  4. D.Pons
Show the answer and why

Answer: C Cerebrum

Why

The cerebrum is the largest portion of the brain in humans. It performs higher functions such as interpreting touch, vision and hearing, speech, reasoning and learning.

Question 5

A dancer needs good balance and smooth, coordinated movements. Which part of the brain maintains posture and balance?

  1. A.Hypothalamus
  2. B.Cerebellum
  3. C.Thalamus
  4. D.Pons
Show the answer and why

Answer: B Cerebellum

Why

The cerebellum maintains posture and balance. It also makes sure that the muscles work together to produce smooth, coordinated voluntary movements. The hypothalamus controls homeostasis, the thalamus is concerned with sensation, and the pons is a bridge of axon bundles.

Question 6

Which part of the brain is the center for homeostatic control of the internal environment, including body temperature?

  1. A.Thalamus
  2. B.Hypothalamus
  3. C.Pons
  4. D.Medulla oblongata
Show the answer and why

Answer: B Hypothalamus

Why

The hypothalamus is the center for homeostatic control of the internal environment. It receives signals about the state of the body and regulates thirst, appetite and body temperature. The thalamus is mainly concerned with sensation.

Question 7

The word pons means "bridge" in Latin. Which statement about the pons is correct?

  1. A.It contains bundles of axons travelling between the cerebellum and the rest of the CNS.
  2. B.It is the center for homeostatic control of the internal environment.
  3. C.It lies under the occipital lobe of the cerebrum.
  4. D.It is the largest part of the hindbrain.
Show the answer and why

Answer: A It contains bundles of axons travelling between the cerebellum and the rest of the CNS.

Why

The pons contains bundles of axons travelling between the cerebellum and the rest of the CNS, which is why it is called a bridge. Option B describes the hypothalamus. Option C describes the cerebellum. Option D also describes the cerebellum.

Question 8

Which part of the brain contains reflex centers for regulating heartbeat and blood pressure?

  1. A.Cerebrum
  2. B.Cerebellum
  3. C.Medulla oblongata
  4. D.Thalamus
Show the answer and why

Answer: C Medulla oblongata

Why

The medulla oblongata contains a number of reflex centers for regulating heartbeat, breathing and blood pressure. It also contains reflex centers for vomiting, coughing, sneezing, hiccuping and swallowing.

Question 9

In the brain and spinal cord, which type of matter is made up mainly of neuron cell bodies?

  1. A.Gray matter
  2. B.White matter
  3. C.Cerebrospinal fluid
  4. D.Dura mater
Show the answer and why

Answer: A Gray matter

Why

Gray matter is primarily made up of neuron cell bodies. White matter consists of bundled axons. In the spinal cord, white matter forms the outer layer, while in the brain it is mostly in the interior.

Question 10

Which of the following is NOT a function of cerebrospinal fluid (CSF)?

  1. A.It acts as a cushion that supports the weight of the brain.
  2. B.It helps to maintain a uniform pressure around the brain and spinal cord.
  3. C.There is a limited exchange of nutrients and waste products between neurones and CSF.
  4. D.It carries light rays to the retina so that images can be formed.
Show the answer and why

Answer: D It carries light rays to the retina so that images can be formed.

Why

CSF cushions the brain, helps keep the pressure uniform, and allows a limited exchange of nutrients and waste with neurones. Carrying light rays to the retina is not a function of CSF. Light rays pass through the parts of the eye such as the cornea and lens.

The app holds 12 questions on this unit, marked as you go. These are the first 10.

The textbook pages for unit 5

Unit 5 runs from page 236 to page 332 of the Ministry of Education edition.

Ministry of Education edition, English, 358 pages

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All Grade 12 Biology short notes

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