cells

Question 1

what is in an animal cell (4)

Answer 1

nucleus
cytoplasm
cell membrane
mitochondria

Question 2

what is in a plant cell (7)

Answer 2

nucleus
cytoplasm
cell membrane
mitochondria
cell wall
chloroplast
vacuole

Question 3

function of a cell wall

eukaryotic, prokaryotic or both

Answer 3

impermeable coating around the cell providing protection and support

both

Question 4

function of a cell membrane

eukaryotic prokaryotic or both

Answer 4

semi-permeable barrier controlling what goes in and out of the cell

both

Question 5

function of the nucleus

eukaryotic prokaryotic or both

Answer 5

contains a cell’s DNA

eukaryotic

Question 6

function of the chloroplast

eukaryotic prokaryotic or both

Answer 6

site of photosynthesis which produces glucose for the organism

eukaryotic

Question 7

function of the cytoplasm

eukaryotic prokaryotic or both

Answer 7

site of chemical reactions

both

Question 8

function of the mitochondria

eukaryotic prokaryotic or both

Answer 8

site of respiration which releases energy

eukaryotic

Question 9

function of the ribosome

eukaryotic prokaryotic or both

Answer 9

site of protein synthesis

both

Question 10

function of the plasmid

eukaryotic prokaryotic or both

Answer 10

small ring of DNA

prokaryotic

Question 11

explain the characteristics of prokaryotic cells

Answer 11

• they are bacteria
• they do not contain membrane bound organelles
• all single celled organisms (and a few multi-cellular ones) are prokaryotic
• their DNA is not bound by a membrane (no nucleus) but it is free within the cell

Question 12

explain the characteristics of a eukaryotic cell

Answer 12

• most multi-cellular organisms are eukaryotic
• they contain membrane bound organelles
• they have DNA bound by a membrane

Question 13

define cell specialisation

Answer 13

cells become specialised to perform certain roles within an organism

the process of cell specialisation is called cell differentiation

Question 14

what are stem cells and what makes them different to most cells

Answer 14

stem cells are undifferentiated and can still divide to make more of themselves

most cells are specialised so therefore cannot divide to create more of themselves

Question 15

define pluripotent and multipotent

Answer 15

pluripotent are stem cells that can become any type of body cell

multipotent are stem cells that can only be certain blood cells

Question 16

what are animal stem cells

Answer 16

there are two types - adult and embryonic stem cells

adult stem cells are taken from a small number of places within a developed organism (like bone marrow) and are multipotent

embryonic stem cells are taken from a developing embryo and are pluripotent

Question 17

how can stem cells be used

Answer 17

stem cells from adults or embryos can grow in a lab to produce many cells of the same type

through cell signalling they can be directed to differentiate into other cell types

they can help replace lost skin, cure diseases such as diabetes, help people with paralysis etc

Question 18

ethics of embryonic stem cells

Answer 18

the embryonic stem cells are taken from the embryo at an early stage in development (just a few cells) so this kills the embryo

there is an issue of consent - embryos do not give consent to donate their cells

adult stem cells are less useful as they don’t differentiate into as many cell types but can be taken from donors/patients

Question 19

define cell division

Answer 19

to make new cells all the DNA in the nucleus first has to be copied during a rest phase in the cell cycle

the new cells (daughter cells) can now receive an exact copy of original cell’s (parent cell) DNA

this is essential for organisms to grow, repair damage or replace cells.
only stem cells can divide - specialised cells can no longer divide

Question 20

define chromosomes

Answer 20

they are made of DNA which is tightly wound around proteins

they are found in the nucleus

DNA has regions called genes - each gene is the code to make a specific protein

protein controls all functions of the body

Question 21

define binary fission

Answer 21

bacteria undergo division called binary fission

they reproduce themselves to make an exact copy

they can do this approximately every 20 minutes

     n (1 x 2  ) - n is the number of 20 minute periods in the time

Question 22

explain the cell cycle

Answer 22

stage 1 - INTERPHASE
cell grows; organelles increase in number
DNA duplicates

stage 2 - MITOSIS
the chromosomes are separated to two sides of the cell
the nucleus splits

stage 3 - CYTOKINESIS
the cytoplasm and cell membrane split
two new, genetically identical cells are formed