(Paper 1 Content Knowledge) 1.2 Cells: Division, Differentiation, Cloning

Question 1

Chromosomes carry genetic information in what molecule?

Answer 1

DNA (Deoxyribonucleic acid)

Question 2

What type of cell division ensures that when a cell divides, each new cell produced has the same genetic information?

Answer 2

Mitosis

Question 3

chromosomes that contains the code for the production of a particular protein are called what?

Answer 3

Genes

Question 4

What cell organelle in eukaryotic cells contains chromosomes?

Answer 4

Nucleus

Question 5

Where in prokaryotic cells are chromosomes found?

Answer 5

floating freely in the cytoplasm with additional DNA in plasmids

Question 6

Each human body typically contains how many chromosomes?

Answer 6

46

Question 7

How many pairs of chromosomes are typically found in humans?

Answer 7

23 pairs

Question 8

In typical biological females, chromosomes are identical in shape. What is the shape of chromosome pairs in females?

Answer 8

XX

Question 9

In typical biological males, what is the shape of a chromosome pair?

Answer 9

XY

Question 10

What are the two reasons necessitating cell division?

Answer 10

1. For the growth of the organism
2. If an organism becomes injured or damaged and requires new cells

Question 11

What is the cycle called for the growth and division of cells?

Answer 11

the cell cycle

Question 12

What is the first stage of mitosis?

Answer 12

The DNA replicates to form two copies of each chromosome

Question 13

What is the second stage of mitosis?

Answer 13

The nuclear membrane begins to break down and the chromosomes line up in the centre of the parent cell

Question 14

What is the third stage of mitosis?

Answer 14

One set of chromosomes is pulled to each side of the cell and the nucleus divides

Question 15

What is the fourth stage of mitosis?

Answer 15

The cytoplasm and cell membrane divide to form two identical cells.

Question 16

When a cell divides through mitosis and forms identical new cells, what are the new cells called?

Answer 16

Daughter cells

Question 17

What formula is used to estimate the length of time spent in different phases of the cell cycle?

Answer 17

(observed number of cells at that stage / total number of observed cells) x total length of time of the cell cycle

Question 18

What are stem cells?

Answer 18

Stem cells are cells that have not undergone differentiation
.

Question 19

What are undifferentiated cells?

Answer 19

future specialised cells that have not yet undergone differentiation.

Question 20

Give an example of tissue that contains stem cells.

Answer 20

Early embryonic tissue of a fertilised egg

Question 21

If embryonic stem cells are removed from an egg, what can we do with them (as scientists)?

Answer 21

specialise them into any type of cell

Question 22

True or false, adults DO NOT have any stem cells?

Answer 22

False

Adult stem cells are found in limited numbers at certain locations in the body.

Question 23

Name 5 places where adult stem cells are located?

Answer 23

Any 5 from:

brain
eyes
blood
heart
liver
bone marrow
skin
muscle

Question 24

Can adult stem cells differentiate into any type of cell?

Answer 24

No

Adult stem cells can differentiate into related cell types only, for example, bone marrow cells can differentiate into blood cells and cells of the immune system but not other cell types.

Question 25

Name two conditions we can successfully treat with stem cells?

Answer 25

Diabetes and paralysis

Question 26

Will a human body reject stem cells if treated with them?

Answer 26

No Stem cells will not be rejected by the person receiving them, so they can be used for medical treatments.

Question 27

What is one medical risk of stem cell transfusion?

Answer 27

viral infection transference

Question 28

What are 2 other issues with stem cell transfusion?

Answer 28

ethical considerations AND religious objections Some people's ethical and religious beliefs mean they oppose the use of human embryonic tissue as it comes from a fertilised egg .

Question 29

Where in plants does cell division occur

Answer 29

meristems

Question 30

What type of cells can meristem cells differentiate into?

Answer 30

All types of plant cells at any point of a plants lifecycle

Question 31

State one way that we can use the stem cells of meristems in plants?

Answer 31

We can make genetically identical plants cheaply and efficiently.

Question 32

Give 2 reasons for the genetic cloning of plants?

Answer 32

Save the endangered species of plants. We can make crops that are resistant to pathogens and pests to protect food supply

Question 33

3 reasons why cells in the animal circulatory system are specialised?

Answer 33

Transport substances, defend the body, regulate temperature

Question 34

2 reasons why cells in the animal excretory system are specialised?

Answer 34

Remove waste products and unwanted substances, regulate the water content of the body

Question 35

1 reason why cells in the animal muscular system are specialised?

Answer 35

Bring about movement

Question 36

2 reasons why cells in the animal nervous system are specialised?

Answer 36

Respond to internal and external stimuli and conditions, carry messages for the body work as a coordinated whole

Question 37

2 reasons why cells in the animal respiratory system are specialised?

Answer 37

Deliver oxygen for respiration and remove waste

Question 38

1 reason why cells in the animal reproductive system are specialised?

Answer 38

Bring about fertilisation to produce new offspring

Question 39

4 reasons why cells in the animal skeletal system are specialised?

Answer 39

To bring about movement, support and protect internal structures, produce blood cells, store and release calcium

Question 40

Name 3 types of specialised cells found in plant leaves

Answer 40

Palisade mesophyll cells, spongy mesophyll cells, guard cells

Question 41

Name 2 types of specialised cells found in plant phloem

Answer 41

Sieve tube cells, companion cells

Question 42

Why are palisade mesophyll cells specialised?

Answer 42

Carry out photosynthesis

Question 43

2 reasons why spongy mesophyll cells are specialised

Answer 43

1. Allow gases to circulate for the exchange of gases between the leaf and the environment. 2. carry out some photosynthesis

Question 44

Why are guard cells specialised?

Answer 44

Open and close to control the exchange of gases – carbon dioxide, water vapour and oxygen

Question 45

Why are the cells of the sieve tubes in the phloem specialised?

Answer 45

Transport products of photosynthesis, including sugars and amino acids, from the leaf to where they are needed

Question 46

What is the specialised role of companion cells?

Answer 46

Provide the energy required for transporting substances in sieve tubes

Question 47

What is the specialised role of cells in xylem vessels?

Answer 47

Transport water and dissolved minerals from the roots, up the plant

Question 48

What is the role of meristem cells in plants?

Answer 48

Produce new cells as they divide, keep a steady rate of stem cell production

Question 49

What type of cells are removed from plants for cloning and placed in tissue culture?

Answer 49

meristematic cells

Question 50

When cloning plant cells, why are meristematic cells placed in a culture medium containing agar jelly?

Answer 50

to provide support and water for the growing cells, along with nutrients and plant hormones to stimulate growth and cell division.

Question 51

Does cloning in plants always occur artificially?

Answer 51

No Cloning in plants also occurs naturally, for instance, in runners and in strawberry plants. An older, simpler method of cloning plants that gardeners use to produce new, identical plants is by taking cuttings .

Question 52

Which two types of stem cells are used to treat chronic conditions in humans

Answer 52

embryonic stem cells adult stem cells

Question 53

Can stem cells be used to treat multiple sclerosis (MS)?

Answer 53

Yes, stem cells can be used to treat MS

Question 54

What is the advantage/disadvantage debate of the use of human embryonic stem cells?

Answer 54

Embryonic stem cells can differentiate into a wider range of cell types, but are difficult to obtain, and their use raises ethical challenges. The best source is the five-day-old embryo. Exam tip: Consider your position on this topic and come up with a list of reasons for/against drawing on your knowledge from the whole course. You may have a 6-8 mark question on this!

Question 55

Two reasons for adult bone marrow stem cell transplants in humans?

Answer 55

cases of blood cancer such as leukaemia and lymphoma When blood cells have been destroyed by conventional cancer treatment and chemotherapies

Question 56

Describe 5 clinical issues of therapeutic cloning

Answer 56

There is no guarantee how successful these therapies will be, for example the use of stem cells in replacing nerve cells lost in Parkinson’s disease patients. The current difficulty in finding suitable stem cell donors. The difficulty in obtaining and storing a patient’s embryonic stem cells. These would have to be collected before birth - some clinics offer to store blood from the umbilical cord when a person is born. Mutations have been observed in stem cells cultured for a number of generations, and some mutated stem cells have been observed to behave like cancer cells. Cultured stem cells could be contaminated with viruses, which would be transferred to a patient.

Question 57

Describe 4 ethical critiques of therapeutic cloning in humans

Answer 57

A source of embryonic stem cells is unused embryos produced by in vitro fertilisation (IVF) For therapeutic cloning is it right to create embryos for therapy, and destroy them in the process? Embryos could come to be viewed as a commodity, and not as an embryo that could develop into a person. At what stage of its development should an embryo be regarded as, and treated as a person?

Question 58

Describe the social issues involved with therapeutic cloning in humans

Answer 58

Educating the public about what stem cells can and can't do is important. Whether the benefits of stem cell use outweigh the objections. Much of the research is being carried out by commercial clinics, so reported successes are not subject to peer review. Patients could be exploited by paying for expensive treatments and being given false hope of a cure as stem cell therapies are only in their developmental stages.