Cell Division and Specialisation

Question 1

what functions are needed for any organism to stay alive

Answer 1

support/structure
exchange (with environment)
digestion
respiration
reproduction

Question 2

cell

Answer 2

basic building block

Question 3

tissue

Answer 3

group of cells with similar structure and similar function

Question 4

organ

Answer 4

group of tissues working together with a specific function

Question 5

organ system

Answer 5

group of organs working together with a specific function

Question 6

organism

Answer 6

group of organ systems that perform all functions necessary to stay alive

Question 7

egs of cell -> tissue -> organ -> organ system

Answer 7

Question 8

specialised

Answer 8

having different adaptations to help carry out specific function

Question 9

nerve cell

Answer 9

Question 10

what are muscle cells

Answer 10

Question 11

striated muscle cells diagram

Answer 11

Question 12

sperm cells

Answer 12

Question 13

root hair cells

Answer 13

absorb water and mineral ions from soil
underground so no chloroplast

Question 14

photosynthetic cells

Answer 14

= palisade cell, long and thin so lots can fit into top layer of leaf

Question 15

xylem cells

Answer 15

xylem is a transport tissue in plants that carries water and mineral ions from roots to highest leaves (made up of xylem cells)
UNIDIRECTIONAL TRAVEL
cells are dead?

Question 16

phloem cells

Answer 16

Question 17

mitosis

Answer 17

DNA in chromosomes copies itself ready for mitosis. most time is spent in this phase (interphase)

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

Chromosomes and their copies line up in the middle of the cell (metaphase)

Chromosomes and their copies are pulled to different ends of the cell (anaphase)

New membranes form around the chromosomes at each end of the cell (telophase)

The cell membrane pinches in and eventually divides into two daughter cells (cytokinesis)

Question 18

cell cycle

Answer 18

interphase (DNA replication and growth) - cell gets ready to divide, cell grows, DNA duplicates, more organelles made

mitosis - genetic material separates and cell gets ready to divide into 2 daughter cells

cytokinesis (cell division) - cytoplasm and cell membrane split, 2 new daughter cells are made

Question 19

cells divide for:

Answer 19

growth (hair, nails)
development (embryos, muscles)
replacement (skin, blood cells)

Question 20

normal cell division

Answer 20

regulated by genes - ensure cells only divide when needed, then stop

apoptosis: body can destroy cells that are old/damaged (controlled cell death)

Question 21

tumour

Answer 21

(caused by mutation) cells growing abnormally and uncontrolled

Question 22

benign vs malignant tumours

Answer 22

Question 23

metastases

Answer 23

secondary tumours

Question 24

causes of cancer

Answer 24

lifestyle:
smoking
obesity (bowel)

viruses:
HPY (cervical)

genetics:
faulty BRCA gene (high risk of breast cancer)

carcinogens:
asbestos (lung)
alcohol (liver)
UV exposure (skin)

Question 25

stem cell

Answer 25

undifferentiated cell that has the potential to become any type of cell needed

Question 26

what happens during first few days after fertilisation

Answer 26

stem cells divide

Question 27

differentiation (and eg)

Answer 27

cells developing structural differences enabling them to carry out a specific function

eg cytoplasm and cell membrane elongate making connections over large distances, forming a nerve cell

Question 28

differentiation in animals vs plants

Answer 28

plant can keep differentiating throughout their life
differentiation is reversible in plants

Question 29

how can stem cells differentiate into any cell

Answer 29

they have access to all genes

Question 30

adult / somatic stem cells? why are they needed?

Answer 30

tissue-specific / multi potent stem cells
- they can only differentiate into one type of tissue (with limited types of cells)
- hard to find!
eg bone marrow

because not all cells can undergo mitosis (eg RBCs, skin cells)

Question 31

bone marrow

Answer 31

soft inner tissue of bones where blood cells are formed
rapidly divide and differentiate to form a variety of cells
can only create blood cells (RBCs, WBCs, platelets)

Question 32

plant differentiation

Answer 32

• differentiate throughout their life
• undifferentiated cells form at meristems (roots and shoots) where mitosis is almost continuous
• cell don’t differentiate until they are at their final position in the plant
• not permanent- cells can revert back, relocate and respecialise

Question 33

therapeutic cloning

Answer 33

a way of producing stem cells with the same genetic makeup as the patient

Question 34

why are embryonic stem cells useful (egs)

Answer 34

dysfunctional/damaged cells that can’t repair themselves cause health problems:
- pancreatic cells -> type 1 diabetes
- spinal cord neurones -> paralysis
- cardiac muscle fibres after heart attack
- brain neurones -> Alzheimer’s disease

Question 35

why is therapeutic cloning useful (what are the alternatives)

Answer 35

although stem cells can be taken from early developing embryos and stimulated to grow into specific body cells
there is a risk of rejection if coming from a donated embryo - lifelong need for immunosuppressants

there would be fewer problems if it came from a family member or from donor with closely matched tissue types