Topic 2: Cells and Control

Question 1

What are adult stem cells?

Answer 1

Stem cells that can differentiate into a limited range of cell types, e.g. bone marrow stem cells.

Question 2

What is anaphase?

Answer 2

The third stage of mitosis in which the chromatids are pulled to opposite poles of the cell by spindle fibres.

Question 3

What is asexual reproduction?

Answer 3

A form of reproduction involving a single parent that creates genetically identical offspring.

Question 4

What is an axon?

Answer 4

A long fibre that conducts nerve impulses away from the cell body.

Question 5

What is cancer?

Answer 5

A non-communicable disease caused by changes in the cell that lead to uncontrolled growth and division.

Question 6

What is a cataract?

Answer 6

A cloudy patch which forms on the lens of the eye and prevents light from entering normally. Affected individuals have blurred vision, difficulty seeing the intensity of colours and problems with glare. It is treated using surgery to exchange the clouded lens for a synthetic one.

Question 7

What is the cell cycle?

Answer 7

A series of events that take place in a cell, involving cell growth, DNA replication and cell division.

Question 8

What is cell differentiation?

Answer 8

The process by which an undifferentiated cell becomes specialised for its function.

Question 9

What is cell elongation?

Answer 9

The process by which cells expand and enlarge, enabling the growth of a plant.

Question 10

What is the central nervous system (CNS)?

Answer 10

The brain and spinal cord.

Question 11

What is the cerebellum?

Answer 11

The region of the brain that controls muscle coordination and non-voluntary movement (e.g. balance, posture).

Question 12

What is a cerebral hemisphere?

Answer 12

One half of the cerebrum. The left hemisphere controls muscles on the right side of the body and vice versa.

Question 13

What is the cerebrum?

Answer 13

The largest region of the brain consisting of two hemispheres. It is responsible for movement, memory, intelligence, language and vision.

Question 14

What is a chromatid?

Answer 14

One ‘arm’ of a replicated chromosome.

Question 15

What is a chromosome?

Answer 15

A long, coiled molecule of DNA that carries genetic information in the form of genes.

Question 16

What is colour blindness?

Answer 16

A deficiency of the eye that makes it difficult to distinguish between colours.

Question 17

What are cone cells?

Answer 17

Cells found in the retina that are sensitive to high light intensity (bright light) and which detect different colours.

Question 18

What is the cornea?

Answer 18

The transparent outer covering that reflects light entering the eye.

Question 19

What is a CT scan?

Answer 19

An imaging technique that uses X-rays to create detailed images of internal organs.

Question 20

What is cytokinesis?

Answer 20

The division of the cytoplasm at the end of mitosis to produce two new daughter cells.

Question 21

What are dendrites?

Answer 21

Short, branched extensions of dendrons that provide a large surface area to receive nerve impulses from other neurones.

Question 22

What is a dendron?

Answer 22

Branched extensions of a nerve cell body that connect to other neurones and carry impulses towards the body.

Question 23

What is a diploid cell?

Answer 23

A cell that contains two copies of each chromosome (i.e. a full set of chromosomes).

Question 24

What is an effector?

Answer 24

An organ, tissue, or cell that produces a response to a stimulus.

Question 25

What are embryonic stem cells?

Answer 25

Stem cells found in very early embryos that are unspecialised and capable of differentiating into any cell type.

Question 26

What is the eye?

Answer 26

A sense organ containing receptors sensitive to light intensity and colour.

Question 27

What is growth?

Answer 27

An increase in mass or size.

Question 28

What is a haploid cell?

Answer 28

A cell that contains a single copy of each chromosome (i.e. half the number of chromosomes).

Question 29

What is interphase?

Answer 29

The longest stage of the cell cycle that involves cell growth, the synthesis of new organelles and DNA replication.

Question 30

What is the iris?

Answer 30

A pigmented ring of muscles that controls the size of the pupil to alter how much light enters the eye.

Question 31

What is the lens?

Answer 31

A transparent, biconvex structure that refracts light, focusing it onto the retina.

Question 32

What is long-sightedness?

Answer 32

A defect of the eye where nearby objects appear out of focus due to the convergence of light rays behind the retina. It occurs when the eyeball is too short or the lens is less elastic. It is corrected using a convex lens.

Question 33

What is the medulla oblongata?

Answer 33

The region of the brain that regulates unconscious activities such as breathing and heart rate.

Question 34

What is meristem tissue?

Answer 34

Plant tissues containing undifferentiated stem cells.

Question 35

What is metaphase?

Answer 35

The second stage of mitosis in which the chromosomes align at the cell equator.

Question 36

What is mitosis?

Answer 36

A form of cell division that produces two genetically identical daughter cells (with a full set of chromosomes) from one parent cell.

Question 37

What is a motor neurone?

Answer 37

A neurone that carries nerve impulses from the central nervous system to the effectors.

Question 38

What is the myelin sheath?

Answer 38

An electrically insulating layer that surrounds the axon and increases the speed of nerve impulses.

Question 39

What are neurones?

Answer 39

Nerve cells adapted to quickly transmit nerve impulses. They are the functional units of the nervous system.

Question 40

What are neurotransmitters?

Answer 40

Chemicals that are used for communication between neurones and their target cells.

Question 41

What is a percentile chart?

Answer 41

A chart used to monitor growth or time. Measurements (e.g. fetal length or head circumference) can be compared to the expected values at a certain age enabling the identification of abnormal patterns in development.

Question 42

What is a PET scan?

Answer 42

An imaging technique used to assess the structure and function of the brain through the use of radioactive chemicals. Comparisons to a normal brain can highlight unusually active or inactive areas.

Question 43

What is prophase?

Answer 43

The first stage of mitosis in which the chromosomes condense and the nuclear membrane breaks down.

Question 44

What is the pupil?

Answer 44

A hole in the centre of the iris that allows light rays to enter the eye.

Question 45

What is a reflex?

Answer 45

A rapid and automatic response to a stimulus by the body.

Question 46

What is a reflex arc?

Answer 46

The pathway of neurones involved in a reflex action.

Question 47

What is a relay neurone?

Answer 47

A neurone that carries nerve impulses from sensory neurones to motor neurones within the central nervous system.

Question 48

What is the retina?

Answer 48

A light sensitive layer at the back of the eye composed of rod and cone cells. It converts light energy into neural signals which are sent to the brain.

Question 49

What are rod cells?

Answer 49

Cells found in the retina that are sensitive to low light intensity (dim light).

Question 50

What is a sensory neurone?

Answer 50

A neurone that carries nerve impulses from the receptors to the central nervous system.

Question 51

What is a sensory receptor?

Answer 51

A specialised structure that detects a specific type of stimulus.

Question 52

What is short-sightedness?

Answer 52

A defect of the eye where distant objects appear out of focus due to the convergence of light rays in front of the retina. It is corrected using a concave lens. ## Footnote This occurs when the eyeball is too long or the lens is too thick and too rounded.

Question 53

What are stem cells?

Answer 53

Cells that are unspecialised and capable of differentiating into a range of different cell types.

Question 54

What is a synapse?

Answer 54

A small gap between neurones across which a nerve impulse is transmitted via neurotransmitters.

Question 55

What is telophase?

Answer 55

The final stage of mitosis in which the spindle fibres break down, two new nuclear envelopes form around the daughter cells and the chromosomes disappear.