Section 2 - Cells and Control

Question 1

Describe chromosomes in the context of genetic information.

Answer 1

Chromosomes are coiled DNA molecules found in the nucleus of cells, carrying genetic information. Most cells have two copies of each chromosome, one from the mother and one from the father.

Question 2

What is the significance of chromosomes being diploid in body cells?

Answer 2

Having two copies of each chromosome in body cells makes them diploid, ensuring genetic diversity and stability.

Question 3

Define mitosis and its role in cell division.

Answer 3

Mitosis is the process of cell division where a cell divides to produce two identical cells, each containing the same number of chromosomes as the original cell.

Question 4

How do multicellular organisms utilise mitosis in the cell cycle?

Answer 4

Multicellular organisms use mitosis for growth, repair, and to replace damaged cells during the cell cycle.

Question 5

Describe asexual reproduction and its connection to mitosis.

Answer 5

Asexual reproduction involves using mitosis to reproduce without genetic recombination, resulting in offspring that are genetically identical to the parent organism.

Question 6

Describe the main stages of the cell cycle.

Answer 6

The main stages of the cell cycle include interphase (growth and DNA replication phase) and mitotic phase (mitosis and cytokinesis).

Question 7

What happens during prophase in mitosis?

Answer 7

During prophase in mitosis, the genetic material inside the nucleus condenses into visible chromosomes, the nuclear membrane disintegrates, and the chromosomes move towards the centre of the cell.

Question 8

How do chromosomes align in metaphase of mitosis?

Answer 8

chromosomes line up at the centre of the cell, forming a metaphase plate.

Question 9

Explain the role of spindle fibres in anaphase of mitosis.

Answer 9

During anaphase, spindle fibres pull the chromosomes apart towards opposite poles of the cell, ensuring each daughter cell receives a complete set of chromosomes.

Question 10

What is the significance of cytokinesis in the cell cycle?

Answer 10

Cytokinesis is the division of the cytoplasm following mitosis, resulting in two daughter cells with identical genetic material.

Question 11

Describe what happens during telophase of mitosis.

Answer 11

Membranes form around each set of chromosomes, creating the nuclei of the two new cells. The cytoplasm and cell membrane then divide to complete cytokinesis.

Question 12

Define cytokinesis in the context of cell division.

Answer 12

Cytokinesis is the process where the cytoplasm and cell membrane divide, resulting in the formation of two separate daughter cells after nuclear division.

Question 13

How can you calculate the number of cells after multiple divisions of a cell by mitosis?

Answer 13

The formula to calculate the number of cells after ‘n’ divisions of mitosis is: number of cells = 2^n.

Question 14

Do daughter cells produced through mitosis contain the same sets of chromosomes as the parent cell?

Answer 14

Yes, daughter cells produced through mitosis are genetically identical diploid cells containing the same sets of chromosomes as the parent cell.

Question 15

Describe the genetic similarity between the two daughter cells produced at the end of mitosis.

Answer 15

The two daughter cells produced at the end of mitosis are genetically identical to each other and to the parent cell, containing the same sets of chromosomes.

Question 16

What are the stages of mitosis?

Answer 16

.Prophase
.Metaphase
.Anaphase
.Telophase
.Cytokinesis

Question 17

Describe the process of cell differentiation.

Answer 17

differentiation is the process by which a cell changes to become specialized for its job, allowing multicellular organisms to work more efficiently.

Question 18

Do plants grow mainly through cell elongation or cell division?

Answer 18

Plants mainly grow through cell elongation, where a plant cell expands to make the cell bigger and the plant grow.

Question 19

Define growth in the context of plants and animals.

Answer 19

Growth is an increase in size or mass in plants and animals, involving processes like cell division, differentiation, and elongation.

Question 20

How does cell division contribute to growth in animals?

Answer 20

All growth in animals happens by cell division, with cells dividing at a fast rate when young and mainly for repair in adulthood to replace old or damaged cells.

Question 21

Describe the role of cell elongation in plant growth.

Answer 21

Cell elongation in plants is the main contributor to growth in height, where plant cells expand to increase size and promote overall plant growth.

Question 22

Define cancer in terms of cell division.

Answer 22

Cancer is a case of uncontrolled cell division, where a change in genes controlling cell division leads to uncontrollable cell growth.

Question 23

How is a tumour formed in the context of cell division?

Answer 23

A mass of abnormal cells called a tumour is formed when cells divide uncontrollably due to changes in genes controlling cell division.

Question 24

What is the purpose of using percentile charts for monitoring growth?

Answer 24

Percentile charts are used to assess a child’s growth over time, highlighting any problems like obesity, malnutrition, or dwarfism.

Question 25

Do percentile charts help in tracking a baby’s growth after birth?

Answer 25

Yes, percentile charts are used to regularly monitor a baby’s growth after birth to ensure it is growing normally.

Question 26

Describe the process of plotting measurements on growth charts.

Answer 26

Measurements like length, mass, and head circumference are taken and plotted on growth charts to show percentiles for different ages.

Question 27

Define ‘percentiles’ in the context of growth charts.

Answer 27

Percentiles on growth charts indicate the percentage of babies of the same age who have measurements below a certain value.

Question 28

How do doctors use growth charts to monitor babies’ development?

Answer 28

Doctors investigate if a baby’s size is consistently above or below certain percentile lines, indicating potential issues with growth.

Question 29

Do babies always fall exactly on a specific percentile line on growth charts?

Answer 29

No, babies vary in size, but their measurements are compared to percentile lines to assess their growth relative to other babies of the same age.

Question 30

Describe a scenario where doctors might investigate a baby’s growth based on growth chart percentiles.

Answer 30

Doctors may investigate if a baby’s size increases or decreases by two or more percentile lines over time, or if there is an inconsistent pattern in growth, such as a small baby with a very large head.

Question 31

What is an embryonic stem cell?

Answer 31

An undifferentiated cell found in early human embryos which has the potential to divide and produce any kind of cell at all

Question 32

Where can stem cells be found in an adult human? What do they do?

Answer 32

Bone marrow. They are used to replace damaged cells, such as blood or skin cells.

Question 33

What type of plant tissue contains stem cells?

Answer 33

Meristem tissue (this is where the growth occurs)

Question 34

Describe two potential risks of using stem cells in medicine.

Answer 34

If a donor stem cells are contaminated with a virus, the virus could be passed on to the recipient. If the cells divide too quickly inside a patient, a tumour may develop. If the transplanted cells aren’t grown using the patient’s own stem cells, their body might reject them.

Question 35

Describe one example of how adult stem cells can be used to cure a disease.

Answer 35

Sickle cell anaemia can sometimes be cured with a bone marrow transplant. The bone marrow contains adult stem cells which produce new healthy blood cells.

Question 36

True or False?
Muscles and glands are examples of receptors.

Answer 36

False. They are effectors

Question 37

In humans, what does the central nervous system (CNS) consist of?

Answer 37

The brain and spinal cord

Question 38

Which type of neurone carries impulses from the CNS to effectors?

Answer 38

motor neurone

Question 39

What is the benefit of an axon having a myelin sheath?

Answer 39

A myelin sheath acts as an electrical insulator, which speeds up the movement of electrical impulses along the axon

Question 40

Describe the difference in function between dendrons and axons.

Answer 40

Dendrons carry nerve impulses towards the cell body, whereas axons carry nerve impulses away from the cell body.

Question 41

Compare the differences in structure of a sensory and a motor neurone.

Answer 41

Sensory neurones have one long dendron and one short axon, whereas motor neurones have many short dendrites and one long axon

Question 42

Describe the structure and function of a relay neurone.

Answer 42

A relay neurone has many short dendrites that carry nerve impulses from sensory neurones to the cell body. It has an axon that carries nerve impulses from the cell body to motor neurones.

Question 43

What is a synapse?

Answer 43

The connection between two neurones

Question 44

How are nerve signals transferred across a synapse?

Answer 44

Neurotransmitters (chemicals) diffuse across the synapse and set off a new electrical impulse in the next neurone.

Question 45

Reflexes do not involve conscious parts of the brain. Why is this advantageous?

Answer 45

It reduces the chance of an injury, as it means that reflexes can be rapid and automatic.