module 2 - 6.4 organisation and specialisation of specialised cells & 6.5 stem cells

Question 1

what happens to cells in multicellular organisms for them to become specialised cells?

Answer 1

differentiation

Question 2

what are the levels of organisation in multicellular organisms?

Answer 2

1. specialised cells
2. tissues
3. organs
4. organ systems
5. organism

Question 3

what are tissues?

Answer 3

collection of 1 or more types of specialised cells, tissue is adapted to perform particular function

Question 4

what are organs?

Answer 4

a collection of tissues that are adapted to perform a particular function

Question 5

what are organ systems?

Answer 5

a collection of organs that are adapted to perform a major function

Question 6

what is the process of making specialised/ differentiated cells called?

Answer 6

differentiation

Question 7

what do all animal, plant and fungal cells begin as?

Answer 7

undifferentiated cells - potential to differentiate into any specialised cells

Question 8

what are undifferentiated cells called?

Answer 8

stem cells

Question 9

what are body cells?

Answer 9

all cells in the body except gametes

Question 10

what do all specialised cells have in common?

Answer 10

they have the same genome as the stem cells

Question 11

why do all specialised cells have the same genome as the stem cells?

Answer 11

because they’re produced by mitosis, so some genes are switched on and some off

Question 12

what can stem cells go through?

Answer 12

cell division

Question 13

why may stem cells go through cell division many times?

Answer 13

to give rise to whole lineages of specialised cells

Question 14

what are stem cells the source of?

Answer 14

new cells for growth, repair and changes to the body plan

Question 15

how controlled is stem cell division?

Answer 15

strictly (come dancing)

Question 16

what is potency?

Answer 16

ability of a stem cell to differentiate into specialised cells

Question 17

what is a totipotent stem cell?

Answer 17

a stem cell that can differentiate into any specialised cell

Question 18

what is a pluripotent stem cell?

Answer 18

stem cell that differentiates into all tissue types (not into extra-embryonic tissues)

Question 19

what is a multipotent stem cell?

Answer 19

a stem cell that can only differentiate into the range of specialised cells found in a tissue

Question 20

what type of cell is a zygote?

Answer 20

totipotent stem cell

Question 21

what is a blastocyst?

Answer 21

a sack of human cells that forms in early pregnancy

Question 22

when the human embryo is a blastocyst, what are the cells and why?

Answer 22

cells are pluripotent because they can form 3 germ layers

Question 23

what are the 3 germ layers?

Answer 23

• endoderm
• mesoderm
• ectoderm

Question 24

what is the endoderm layer used for?

Answer 24

• interior stomach lining
• gastrointestinal tract
• lungs

Question 25

what is the mesoderm layer used for?

Answer 25

• muscle
• bone
• blood
• urogenital

Question 26

what is the ectoderm layer used for?

Answer 26

• epidermal tissues
• nervous system

Question 27

where are plant stem cells found?

Answer 27

meristems or meristematic tissue

Question 28

where are the meristems/ meristematic tissue?

Answer 28

• shoot and root tips where growth by cell division occurs
• also found in vascular bundles between xylem and phloem tissue

Question 29

what is the area called between the xylem and phloem tissue where meristems can be found?

Answer 29

VASCULAR CAMBIUM

Question 30

where do animal stem cells come from?

Answer 30

• embryonic stem cells
• tissue or adult stem cells (located in specific areas after birth)