Cells and Control

Question 1

What can cells be used for?

Answer 1

• Growth
• Development
• Repair

Question 2

What is the cell cycle?

Answer 2

The series of events that take place in a cell that cause it to divide into two daughter cells

Question 3

When the cell is not dividing how is the DNA spread out?

Answer 3

DNA is spread out in long strings

Question 4

When the cell starts to prepare for division, how is the DNA spread out?

Answer 4

DNA condenses into chromosomes (coiled up packets out DNA)

Question 5

How many pairs of chromosomes does a human have?

Answer 5

23 pairs

Question 6

What are the stages of the cell cycle?

Answer 6

• Cellular Growth - the cell gets larger and produces more sub-cellular structures, such as mitochondria and ribosomes
• DNA Replication - chromosomes duplicate, so that each consists of two arms (copies).
  More cell growth.
• Mitosis - The DNA divides in two
• Cytokinesis - The cell divides in two

Question 7

What happens in Interphase?

Answer 7

Cell spends most of its time in interphase

DNA in chromosomes copies itself ready for mitosis

Question 8

What happens in Prophase?

Answer 8

DNA in chromosomes and their copies condenses to become more visible
The membrane around the nucleus disappears

Question 9

What happens in Metaphase?

Answer 9

Chromosomes and their copies line up in the middle of the cell

Question 10

What happens in Anaphase?

Answer 10

Chromosomes and their copies are pulled to different sides of the cells

Question 11

What happens in Telophase?

Answer 11

New membranes form around chromosomes at each end of the cell

Question 12

What happens in Cytokenisis?

Answer 12

The cell membrane pinches in an eventually divides into two daughter cells

Question 13

What are specialised cells?

Answer 13

Cells designed to carry out a specific role in the body

Question 14

What are stem cells?

Answer 14

Cells that are completely undifferentiated

Have the capacity to specialise into any type of cell

Question 15

What is the definition of differentiate?

Answer 15

The process by which cells become specialised for their role

Question 16

What are embryonic stem cells?

Answer 16

• Found in early human embryos

- Can differentiate into any type of cell

Question 17

What are adult stem cells?

Answer 17

• Found in bone marrow

- Can only differentiate into different types of blood cells

Question 18

What are meristems?

Answer 18

They don’t ever fully differentiate and they stay as stem cells throughout the plants life

Question 19

Which two cells have adapted to their roles by having a large surface area?

Answer 19

Root hair cells and red blood cells

Question 20

How does a heart constantly beat without stopping? What adaption does the heart have?

Answer 20

They have a large number of mitochondria

Question 21

What are two key features of stem cells?

Answer 21

• Can divide by mitosis to form into more cells

- Stem cells are able to differentiate into more stem cells

Question 22

Where can you find meristems?

Answer 22

In parts of the plant that are continually growing

Question 23

When a sperm cell fertilises an egg cell, what is formed?

Answer 23

A zygote

Question 24

What’s the next step after a zygote is formed?

Answer 24

The zygote divides by mitosis and forms a group of cells called and embryo

Question 25

What are the cells in an embryo called?

Answer 25

Embryonic, it can differentiate into any kind of cell

Question 26

What is type 1 diabetes caused by?

Answer 26

Damage to the pancreas cells that normally produce insulin

Question 27

What is paralysis sometimes caused by?

Answer 27

By damaged nerve cells

Question 28

What is sickle cell anaemia caused by?

Answer 28

Misshapen red blood cells

Question 29

What is the most common technique to replace faulty cells with functioning ones?

Answer 29

1) Extract embryonic stem cells from early embryos
2) Grow them in a laboratory
3) Stimulate them to differentiate into any type of specialised cell that we want
4) Then give them to the patient to replace their faulty cells

Question 30

What are the drawbacks of the method of replacing faulty cells with functioning ones?

Answer 30

• Requires embryonic stem cells and there’s a very limited supply of them and some ethical issues
• Rejection, the patients immune system may reject the stem cells. And may try to destroy it because it identifies it as foreign

Question 31

How can we reduce the risks of rejection of the embryonic cells in another body?

Answer 31

Giving the patient medicine that supresses their immune system. However, this doesn’t always work.

Question 32

What an alternative for using embryonic stem cells? And why are they a better alternative?

Answer 32

Using adult stem cells instead

• Won’t cause rejection
• Not a limited supply as found in the patient

Question 33

What hold backs are there from using adult cells?

Answer 33

They can only differentiate into different types of blood cells

Question 34

What are two risks of using stem cells for medicine?

Answer 34

• Virus transmission

- Tumour development

Question 35

What is the idea of virus transmission in stem cells medicine?

Answer 35

If the donor stem cells are infected with a virus, when they’re transferred into the patient it can infect the patient

Question 36

What is the idea of tumour development in stem cells medicine?

Answer 36

Because stem cells can divide so quickly, there’s a chance they can get out of control once they’ve been transplanted and this could lead to the development of a tumour

Question 37

What is the ethical objection to using embryonic stem cells?

Answer 37

• They have the potential to create human life and therefore people object to them being used in scientific research.
  However, other people think that curing existing diseases is more important than the right of embryos.

Question 38

What are neurones adapted to do?

Answer 38

Send electrical impulses from one point to another

Question 39

How does a neurone look?

Answer 39

They are long and thin and have a lot of branch connections (which enables them to pass messages onto other nerve cells)

Question 40

What is a synapse?

Answer 40

The small space between two neurones

Question 41

What is the central nervous system made up of?

Answer 41

Brain and spinal cord (where are the ‘thinking’ takes place) and sends out orders to the rest of the body

Question 42

What are sensory neurones?

Answer 42

Carry information from receptors all throughout our body, to the central nervous system

Question 43

What kind of information can sensory neurones carry?

Answer 43

Change in temperature, change in blood stream… etc..

Question 44

What are motor neurones?

Answer 44

Another type of nerve cell that carry’s the impulse from the sensory to the effectors

Question 45

What are effectors?

Answer 45

Generally muscles of glands

Question 46

What is a reflex arc?

Answer 46

A nerve pathway that underlies our unconscious reflex’s

Question 47

What are reflex’s?

Answer 47

They are rapid and automatic responses, which helps us to avoid getting hurt

Question 48

What is the process of the nervous system?

Answer 48

• Pressure from stimulus detected by receptor cells
• Stimulates sensory neurone
• Sensory neurones carry impulse from finger to spinal cord
• In spinal cord, it transfers to relay neurone
• Relay neurone passes it to a motor neurone
• Motor neurone will travel back to an effector

Question 49

What is released across the synapse?

Answer 49

Chemicals