b1 - cell biology

Question 1

where are stem cells found in the human body

Answer 1

in the bone marrow

Question 2

where are chromosomes housed in eukaryotic cells

Answer 2

nucleus

Question 3

how many micrometres in an egg cell

Answer 3

200

Question 4

how big are eukaryotic cells

Answer 4

10 - 100 micrometres

Question 5

how do you perform a light microscope experiment

Answer 5

1. put thin sample of tissue on microscope slide
2. add a few drops of stain e.g. iodine
3. place coverslip on tissue and place slide on microscope stage
4. use objective lens with lowest magnification and focus on the sample
5. increase magnification and refocus

Question 6

which microscope allows scientists to understand the functions of sub-cellular structures

Answer 6

electron microscope

Question 7

which microscope was first used in 1933

Answer 7

electron microscope

Question 8

equation for magnification

Answer 8

size of image / size of real object

Question 9

why do animal cells mostly divide for

Answer 9

to replace cells and repair tissues

Question 10

what sub-cellular structures do animal cells not have

Answer 10

vacuole
chloroplasts
cell wall

Question 11

what are ribosomes for

Answer 11

making proteins

Question 12

what process is chlorophyll needed for

Answer 12

photosynthesis

Question 13

where do most of the cell’s chemical reactions take place

Answer 13

cytoplasm

Question 14

what are the uses of stem cells

Answer 14

plant cloning
therapeutic cloning
stem cell treatments

Question 15

what is therapeutic cloning

Answer 15

a process that produces an embryo that has the same genome as patient

Question 16

where are plant stem cells found

Answer 16

meristem tissue

Question 17

what happens when the cell divides

Answer 17

2 identical cells are created by the division of the cytoplasm and cell membrane

Question 18

what happens during mitosis

Answer 18

the 2 sets of chromosomes are pulled to opposite ends of the cell then the nucleus divides into 2

Question 19

what happens during the initial growth stage

Answer 19

extra ribosomes and mitochondria produced and the cell’s chromosomes are replicated

Question 20

what do chromosomes contain

Answer 20

different genes that produce different proteins

Question 21

what are the stages of the cell cycle

Answer 21

mitosis
initial growth
cell divides

Question 22

what is the cell cycle

Answer 22

the series of events involved in cell growth and division

Question 23

what do acrosomes contain

Answer 23

digestive enzymes

Question 24

what is resolution

Answer 24

the ability to tell apart 2 or more objects that are close

Question 25

what 2 variables matter when using microscopes

Answer 25

magnification and resolution

Question 26

what are the adaptations of muscle cells

Answer 26

lots of mitochondria and protein fibres that contact

Question 27

what happens when a cell differentiates

Answer 27

it becomes a different type of body cell

Question 28

differentiation occurs when cells...

Answer 28

acquire different sub-cellular structures

Question 29

what cells can keep their ability to differentiate and create new tissues

Answer 29

plant cells

Question 30

which sub-cellular structures can be found in prokaryotic cells

Answer 30

single dna loop plasmids cell membrane

Question 31

what is active transport

Answer 31

the net movement of particles against a concentration gradient

Question 32

what does active transport allow

Answer 32

sugar absorption in human gut mineral absorption in plants

Question 33

what is an independent variable

Answer 33

something that is controlled and changed in the experiment

Question 34

what are the features of osmosis

Answer 34

partially permeable membrane net movement of water

Question 35

why does water move by osmosis

Answer 35

so that the concentration is the same on both sides of the membrane

Question 36

what is osmosis

Answer 36

where water moves from an area of high water concentration to low water concentration

Question 37

why can't multicellular organisms rely on diffusion

Answer 37

their cells are too far from the external environment

Question 38

what is the formula for surface area to volume ratio

Answer 38

surface area / volume

Question 39

how does the cell membrane affect diffusion

Answer 39

the larger the surface area the faster the rate of diffusion

Question 40

how does the concentration gradient affect diffusion

Answer 40

the bigger the difference in concentration in 2 areas the faster the diffusion

Question 41

how does temperature affect diffusion

Answer 41

higher = faster

Question 42

what is diffusion

Answer 42

net movement of particles from an area of high concentration to an area of low concentration

Question 43

disadvantage of stem cells

Answer 43

they can transfer viral infections

Question 44

how is a sperm cell specialised for its function

Answer 44

the acrosome in the head contains enzymes so it can penetrate an egg. the middle piece has lots of mitochondria as it needs energy to swim

Question 45

how are nerve cells specialised for their function

Answer 45

thin so can carry messages quickly. branched connections at each end so can connect to other nerve cells to pass messages around the body

Question 46

how are muscle cells specialised for their function

Answer 46

contain mitochondria to provide the energy for muscle contraction. they store glycogen which can be sued for respiration

Question 47

how are root hair cells specialised for their function

Answer 47

large surface area to increase the rate of absorption. lots of mitochondria to provide energy for active transport

Question 48

how are xylem cells specialised for their function

Answer 48

they lose their end wall to form a continuous hollow tube. strengthened by lignin

Question 49

how are phloem cells specialised for their function

Answer 49

sieve tubes - its cytoplasm connects one cell to another companion cells - attached to each sieve tube to provide energy

Question 50

stem cells from meristems in plants can be used to...

Answer 50

clone rare species of plants to protect them from extinction