B2 - Cell Division

Question 1

Which stem cells are found in animals?

Answer 1

Adult stem cells
Embyonic stem cells

Question 2

What are stem cells?

Answer 2

Cells divided by mitosis that are able to differentiate into specialised cells

Question 3

What can embryonic cells differentiate into?

Answer 3

Any type of specialised cell

Question 4

What happens to your stem cells when you stop producing embryonic stem cells?

Answer 4

They can no longer differentiate into absolutely anything

Question 5

What can adult stem cells do?

Answer 5

They can divide by mitosis but can only differentiate into different types of blood cells

Question 6

How many chromosomes does the human body have in each nucleus?

Answer 6

46 chromosomes (23 pairs of 2)

Question 7

What is differentiation?

Answer 7

The process by which a cell changes to become specialised

Question 8

What forms when a sperm cells fertilises an egg cell?

Answer 8

A single cell called a zygote

Question 9

How is an embryo made?

Answer 9

A zygote divides continously by mitosis and in a few days, there is enough cells to form an embryo

Question 10

What are one of the group of cells in an embryo called?

Answer 10

Embryonic stem cells

Question 11

What can adult stem cells only differentiate into?

Answer 11

Different types of blood cells

Question 12

Where are adult stem cells found?

Answer 12

In the bone marrow

Question 13

Since adult stem cells cant form any new tissues like embryonic stem cells, what is their purpose?

Answer 13

They can replace damaged cells to keep us alive

Question 14

Where are plant stem cells found?

Answer 14

Plant tissues called ‘meristems’

Question 15

Where are meristems found?

Answer 15

Areas of the plant that are continuously growing
E.g. tip of roots and tip of (shoots) leaves

Question 16

What are some examples plant stem cells can differentiate into?

Answer 16

Palisade cells
Phloem cells
Xylem cells

Question 17

What is Binary fission?

Answer 17

The process by which prokaryotic organisms, like bacteria, divide and reproduce

Question 18

Is BINARY FISSION the same as MITOSIS?

Answer 18

No

Question 19

Why is Binary fission and mitosis NOT the same?

Answer 19

Mitosis is the process that happen in EURKARYOTIC cells
Binary fission is the process that happens in PROKARYOTIC cells

Question 20

Why is Binary Fission a type of reproduction?

Answer 20

The worn organism has to split into two organisms

Question 21

What type of reproduction is Binary Fission referred to?

Answer 21

Asexual Reproduction

Question 22

What does a bacterial cell need to do in order to divide?

Answer 22

GROW to be big enough to divide into two new cells
REPLICATE ITS GENETIC MATERIAL so there is enough for each new cell

Question 23

How does bacteria divide after it grows and replicates its genetic material?

Answer 23

The two circular chromosomes (original and clone) move away from each other, getting ready to create new cell walls and pull apart

Question 24

If a bacterial cell has a mean dividion time of 30 minutes. How many cells would it produce in 3 hours?

Answer 24

180 mins in 3 hours
6 rounds of division in 3 hours
1x2x2x2x2x2x2 = 64
64 cells

Question 25

What conditions do bacteria like for optimal growth?

Answer 25

Somewhere that is: Warm Moist Has plenty of nutrients

Question 26

If bacteria are in bad conditions for optimal growth what will happen to their division rate?

Answer 26

They will divide more slowly or not at all

Question 27

What is the first stage of the cell cycle?

Answer 27

The DNA replicates to form two copies of each chromosome The cell then grows and copies its internal structures (mitochondria, ribosomes etc.)

Question 28

What is the second stage of the cell cycle?

Answer 28

Mitosis takes place The two sets of chromosomes is pulled to each end of the cell

Question 29

What happens in the third and final stage of the cell cycle?

Answer 29

The cytoplasm and cell membrane divide to form two identical cells

Question 30

Why is mitosis essential to animals and plants?

Answer 30

Essential for growth and development of multicellular organisms

Question 31

What type of reproduction method does mitosis occur in?

Answer 31

Asexual reproduction

Question 32

How are adult stem cells used in medicine?

Answer 32

Used to cure disease

Question 33

What is an example of adult stem cells being used in medicine?

Answer 33

Transferring stem cells from bone marrow from a healthy person to replace faulty blood cells in a patient who needs them

Question 34

What are the advantages of therapeutic cloning?

Answer 34

An embryo is made to have the same genetic material as the patient Wouldnt be rejected by the patients body

Question 35

What age are adult stem cells found in?

Answer 35

People of all ages

Question 36

What is the idea of using stem cells in medicine

Answer 36

To replace faulty cells

Question 37

What are the disadvantages of using embryonic stem cells in medicine?

Answer 37

Ethical issues Patients immune system might reject them

Question 38

What is a disadvantage of using adult stem cells in medicine?

Answer 38

Can only treat blood diseases

Question 39

What is an advantage of using adult stem cells in medicine?

Answer 39

Taken from the patient so it wont be rejected by their immune system

Question 40

What are the risks involved when using stem cells in medicine?

Answer 40

Virus transmission Tumor development - chance they could divide uncontrolably

Question 41

Why do people reject the use of embryonic stem cells in research?

Answer 41

Embryos have fge potential for human life

Question 42

Why do body cells normally have two copies of each chromosome?

Answer 42

One from the mother and one from the father

Question 43

What are the daughter cells in mitosis?

Answer 43

The two identical cells made from the original one

Question 44

What is the name of the cell division prokaryotic cells use to reproduce?

Answer 44

Binary fission

Question 45

Explain the process of Binary fission

Answer 45

The circular DNA and plasmids replicate The cells grows and the circular DNA stands move to opposite ends Cytoplasm begins to divide and new cell memranes form Two daughter cells are produced with random copies of plasmids

Question 46

What happens in a culture medium?

Answer 46

An area of nutrients so bacteria can culture (grow and multiply)

Question 47

What culture medium do you use in the culturing microorganisms practical?

Answer 47

Agar jelly

Question 48

Why are culture mediums not kept above 25°C?

Answer 48

Possibility of harmful pathogens growing

Question 49

How do you culture microorganisms (grow bacteria)?

Answer 49

1. Carefully sterilise all petri dishes, bacterial nutrient broth and agar to kill all unwanted organisms and prevent contamination 2. Sterilise the inoculating loop using a bunsen burner safe5y flame 3. Use adhesive tape to attach the lid of the petri dish to stop it from falling off and preventing contamination 4. Place the agar plate upside down so moisture wont dip down and disrupt the colonies 5, incubate at 25°C

Question 50

What are some antiseptic technique?

Answer 50

Sterillizing equipment - dip in ethanol and then use bunsen burner to burn off bacteria Opening petri dish slightly Clean surfaces

Question 51

A gene is a length of DNA. What type of subdtance does a gene code for?

Answer 51

Protien

Question 52

Most human body cells contain 6 × 10* –12 grams of DNA. What mass of DNA will a human sperm cell contain?

Answer 52

3 x 10* -12

Question 53

What is the name of the type of cell division that produces sperm cells?

Answer 53

Meiosis

Question 54

What are the advantages of embryonic stem cells in medicine?

Answer 54

Can treat a wide variety of diseases Can differentiate into any cell

Question 55

What is Therapeutic cloning?

Answer 55

A process of creating stem cells with the same genes as thr patient to prevent rejection

Question 56

What is the process of Therapeutic Cloning? Use a human skin cell as an example.

Answer 56

Nucleus is taken out the skin cell and put in an egg cell (the egg cell nucleus has been removed) The egg develops into an embryo Stem cell can now differentiate into any cell

Question 57

There are two types of cell division: mitosis and meiosis. (a) Describe three differences between the processes of mitosis and meiosis.

Answer 57

Mitosis produces two daughter cells whereas meiosis produces 4 Mitosis produces cells with 23 pairs (46) chromosomes whereas meiosis produced cells with 23 Mitosis produces genetically indentical cells whereas meiosis produces genetically different cells