Cells and control Topic 2

Question 1

The Stages of Mitosis

Answer 1

Interphase: Cell grows, DNA replicates.
Prophase: Chromosomes condense, nuclear membrane dissolves.
Metaphase: Chromosomes line up in the center.
Anaphase: Chromosomes pulled apart to opposite sides.
Telophase: New nuclear membranes form.
Cytokinesis: Cytoplasm divides, forming two cells.

Question 2

Importance of Mitosis

Answer 2

Mitosis is crucial for:
Growth of organisms.
Repair of damaged tissues.
Asexual reproduction in some organisms.

Question 3

Mitosis and Daughter Cells

Answer 3

Mitosis produces two genetically identical diploid cells.
Each daughter cell has the same number of chromosomes as the parent cell.

Question 4

Cancer and Uncontrolled Cell Division

Answer 4

Cancer occurs when cells divide uncontrollably due to genetic changes, leading to tumors.

Question 5

Growth in Animals vs Plants

Answer 5

Animals: Growth through cell division and differentiation.
Plants: Growth through cell division, elongation, and differentiation.

Question 6

Cell Differentiation

Answer 6

Cell differentiation allows cells to become specialized for specific functions (e.g., muscle cells, nerve cells).

Question 7

Growth Monitoring with Percentile Charts

Answer 7

Percentile charts are used to track growth patterns in children by comparing their size to averages for their age.

Question 8

Stem Cells

Answer 8

Embryonic stem cells can develop into any type of cell.
Adult stem cells maintain and repair tissues.
Meristems in plants are regions where rapid cell division occurs, aiding growth.

Question 9

Stem Cells in Medicine

Answer 9

Benefits: Potential to treat conditions like Parkinson’s and diabetes.
Risks: Ethical concerns, risk of rejection, or uncontrolled growth (tumors).

Question 10

Limitations in Treating Brain and Nervous System Disorders

Answer 10

Brain injuries and tumors are difficult to treat because:
The brain is delicate and hard to access.
Nerve cells do not easily regenerate.

Question 11

Structure and Function of the Brain

Answer 11

Cerebral hemispheres: Responsible for thinking, memory, and senses.
Cerebellum: Coordinates movement and balance.
Medulla oblongata: Controls automatic functions (e.g., breathing, heartbeat).

Question 12

Brain Scanning Technologies

Answer 12

CT scans: Use X-rays to create detailed brain images.
PET scans: Detect areas of high activity in the brain using radioactive tracers.

Question 13

Nervous System – Neurones

Answer 13

Sensory receptors detect stimuli.
Sensory neurones carry impulses to the CNS.
Relay neurones pass signals within the CNS.
Motor neurones send signals to muscles.
Synapses allow communication between neurones using neurotransmitters.

Question 14

Reflex Arc

Answer 14

A reflex arc involves:
1. Sensory neurone (detects stimulus).
2. Relay neurone (in the CNS).
3. Motor neurone (triggers response).
It enables fast, automatic responses.

Question 15

Structure of the Eye

Answer 15

Cornea & lens: Focus light onto the retina.

Iris: Controls the size of the pupil to regulate light entry.

Rod & cone cells: Detect light; rods detect dim light, cones detect color.

Question 16

Eye Defects

Answer 16

Cataracts: Cloudy lens.

Long-sightedness: Difficulty focusing on close objects.

Short-sightedness: Difficulty focusing on distant objects.

Colour blindness: Inability to distinguish some colors.

Question 17

Correcting Eye Defects

Answer 17

Cataracts: Treated with lens replacement.

Long-sightedness: Corrected with convex lenses.

Short-sightedness: Corrected with concave lenses.

Question 18

Maths Skills in Biology

Answer 18

Use percentiles and percentage gain/loss to analyze growth.
Interpret graphs and charts to understand data.
Use scatter diagrams to identify correlations between variables.

Question 19

Investigating the Nervous System

Answer 19

Practical investigations include:

Measuring reaction times to stimuli.
Studying the speed of electrical

impulses in the nervous system.