Cell Division

Question 1

where is the genetic material stored in the cell

Answer 1

nucleus

Question 2

the DNA is arranged in structures call ………………..

Answer 2

chromosomes

Question 3

what does each chromosome carry

Answer 3

different genes

Question 4

what are genes

Answer 4

a gene is a specific section of DNA that codes for the production of one specific protein

Question 5

what do different genes determine

Answer 5

different genes determine the development of specific characteristics

Question 6

in body (somatic) cells how are chromosomes found in

Answer 6

pairs

Question 7

how many chromosomes are in a somatic cell

Answer 7

46 chromosomes , 23 pairs

Question 8

what is it called when the full number of chromosomes are found inside the nucleus of a somatic cell

Answer 8

diploid cell

Question 9

somatic cells in a multicellular organism must be able to divide + produce new cells so that : (4 reasons)

Answer 9

• damaged + old cells are replaced
• tissues + organs can be repaired
• tissues + organs can grow
• the organism itself can grow

Question 10

what are the 2 main stages of the cell cycle

Answer 10

1. Cell growth + DNA replication
2. Mitosis

Question 11

describe the stages in the cell growth phase

Answer 11

1. cells get bigger
2. DNA doubles –> forms 2 copies of each chromosome
3. sub-cellular structures like ribosomes + mitochondria double

Question 12

describe the stages of mitosis

Answer 12

1. chromosomes line up in the middle / equator of the cell
2. half of the chromosomes are pulled to each pole of the cell
3. 2 nuclei form within the cell –> nucleus divides
4. cytoplasm, organelles + cell membrane + nuclei are split to form 2 new daughter cells which are genetically identical

Question 13

what type of reproduction is binary fission

Answer 13

asexual reproduction

Question 14

how is bacteria difference from mitosis

Answer 14

• mitosis is the division of the nucleus BUT bacteria do not have nuclei
• spindle fibres also not formed in binary fission

Question 15

describe the stages of binary fission

Answer 15

• cell replicates DNA
• increase in size
• divide into 2 genetically identical daughter cells

Question 16

stem cells is an …………………. cell

Answer 16

undifferentiated

Question 17

what process do stems cells divide by

Answer 17

mitosis

Question 18

stems cells differentiate into what

Answer 18

into different types of specialised cells

Question 19

what are the 3 types of stems cells

Answer 19

• embryonic stem cells
• adult stem cells
• plant stem cells

Question 20

what is the function of an embryonic stem cell

Answer 20

• stem cells found in early human embryos - can be cloned and made to differentiate into any type of cell = totipotent stem cells

Question 21

describe the function of a adult stem cell

Answer 21

• found in adult bone marrow
• can form many types of cells –> including blood cells

Question 22

where is the adult stem cell found

Answer 22

adult bone marrow

Question 23

where are plant stem cells found

Answer 23

meristems

Question 24

describe the function of a plant stem cell

Answer 24

• stem cells found in plants in meristems
• Meristematic tissue found in the shoot tips + root tips
• can differentiate into any type of plant cell throughout plants entire life

Question 25

what are the uses of embryonic stem cells

Answer 25

- **insulin-producing cells** to treat people with **diabetes** - **neurones** could be used to treat people with **spinal cord injuries** --> paralysis

Question 26

advantages of using embryonic stem cells

Answer 26

- **therapeutic cloning**used to produce ** embryonic stem cells** which have the **same genetic info** as the patient - stem cell produced from the embryo would contain ((same genes as patient** - **prevents cells** being **rejected** by patients body --> can be used for **medical treatment**

Question 27

risks / disadvantages of embryonic stem cells

Answer 27

- grown artificially in a **lab**, may become **contaminated with viruses** --> could be **passed onto patient** - **ethical or religious objections**

Question 28

uses of adult stem cells

Answer 28

- treat some diseases --> **sickle cell anemia**: - stem cell extracted from bone marrow which are used to faulty red blood cells

Question 29

uses of plant stem cells

Answer 29

- produce **clones** of whole plants **quickly + economically** - **Rare species cloned** to protect from **extinction** - **crops** with **desirable features** (e.g. disease resistance) can be **cloned** to produce **large no. of identical plants** for farmers

Question 30

what are the ethical issues for why some people are against the use of stem cells in research

Answer 30

- fell thet human **embryos** are a **potential life** - obtaining stem cells from an embryo **destroys the embryo** + destroys life - embryos **can't give consent** - time + money could be spent to fine **alternative solutions** e.g. find method to turn differentiated adult cell back into stem cell

Question 31

some people are for the use of stem cells in research because:

Answer 31

- fell that **treating + curing existing patients** who are suffering is **more important** than the rights of the embryo - embryos that are used are usually embryos that would be destroyed as biological waste : **extra embryos** generated by **fertility clinics** but are not used