Cell Biology

Question 1

what are the two types of eukaryotic cells we know?

Answer 1

animal and plant

Question 2

what type of prokaryotic cell do we know?

Answer 2

Bacterial

Question 3

what equation can we use to figure out magnification?

Answer 3

magnification = image size/real size

Question 4

what does the nucleus do?

Answer 4

contains genetic material

Question 5

what does the cytoplasm do?

Answer 5

where most of the chemical reactions happen

Question 6

what does the mitochondria do?

Answer 6

where most of the reactions for aerobic respiration take place

Question 7

what does the cell membrane do?

Answer 7

controls what goes in and out

Question 8

what do the ribosomes do?

Answer 8

where proteins are made

Question 9

what does the cell wall do and what is it made from?

Answer 9

it is made from cellulose and it strengthens the cell

Question 10

what do the chloroplasts do?

Answer 10

where photosynthesis occurs

Question 11

what does the permanent vacuole store?

Answer 11

cell sap

Question 12

what two DNA related things does a prokaryotic cell have?

Answer 12

Plasmid (small ring of DNA) and a DNA loop floating in the cytoplasm

Question 13

what do prokaryotes not have?

Answer 13

a true nucleus

Question 14

what are chromosomes?

Answer 14

coiled up lengths of DNA molecules, which carry genes.

Question 15

where are chromosomes found?

Answer 15

in the nucleus, and they are normally in pairs in body cells

Question 16

what is a cell cycle?

Answer 16

a series of stages in which cells divide to produce new cells (eg. mitosis or meiosis)

Question 17

what 3 things does a cell do before it divides?

Answer 17

1: Grows in size
2: Increases the amoubnt of subcellular structures (mitochondria and ribosomes etc)
3: Duplicates its DNA

Question 18

what is mitosis?

Answer 18

mitosis is the stage of the cell cycle when the cell divides

Question 19

what steps are there to mitosis?

Answer 19

1: The cells DNA is double, so there are two copies of each chromosome (this is the parent cell)
2: One set of chromosomes is pulled to each end of the cell
3: The cytoplasm and cell membranes divide
4: Two cells are formed, which are identical to each other and to the parent cell

Question 20

what does mitosis allow?

Answer 20

it allows multicellular organisms to grow and replace cells that have been damaged

Question 21

what is binary fission?

Answer 21

the simple cell division by which bacterial cells replicate. It can happen as often as every 20 minutes if there are enough nutrients and the temperature is suitable.

Question 22

what do we call the two cells prduced in binary fission?

Answer 22

daughter cells

Question 23

what is differentiation?

Answer 23

the process by which a cell changes to become specialised for its job

Question 24

who loses the ability to differentiate cells?

Answer 24

most animal cells lose it at a very early stage, but plant cells never lose the ability.

Question 25

how are sprem cells specialised?

Answer 25

long tail and streamlined head for swimming to the egg

Question 26

how are nerve cells specialised?

Answer 26

long to cover a large distance, and branched to form a network of connections

Question 27

how are xylem and phloem specialised?

Answer 27

xylem cells are hollow and phloem cells have few subcellular structures, so substances can easily flow through them

Question 28

how are muscle cells specialised?

Answer 28

long so they have space to contract, and lots of mitochondria for energy

Question 29

how is a root hair cell specialised?

Answer 29

large surface area for absorbing water and mineral ions from the soil

Question 30

what are stem cells?

Answer 30

undifferentiated cells, which can divide and produce lots more stem cells, and can differentiate unto many other types of cell

Question 31

what can stem cells from adult bone marrow become?

Answer 31

many kinds of cell, eg blood cells

Question 32

what can stem cells from a human embryo become?

Answer 32

any kind of human cell

Question 33

what can stem cells from a plant meristem become?

Answer 33

any kind of plant cell

Question 34

can they be grown in a lab?

Answer 34

yes

Question 35

what uses do stem cells have in medicine?

Answer 35

eg. stem cells could produce nerve cells to treat paralysis, or insulin-producing cells to treat diabetes. In therapeutic cloning, an embryo could be made with the same genes as the patient - then stem cells used from the embryo wouldn’t be rejected by the patient

Question 36

what uses do stem cells have in plants?

Answer 36

produce clones of whole plantd quickly and cheaply, eg. to grow more plants of a rare species, or clone crops with desired features

Question 37

what risk is there to stem cells?

Answer 37

they could get a virus, which could be transferred to the patient

Question 38

What is diffusion?

Answer 38

The spreading out of particles from an area of higher concentration to an area of lower concentration. Only very small molecules can diffuse through cell membranes

Question 39

What 3 factors affect the rate of diffusion?

Answer 39

1: A high concentration gradient 2: A high temperature 3: A large surface area

Question 40

What is osmosis?

Answer 40

The net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration

Question 41

What is active transport?

Answer 41

The net movement of a substance against the concentration gradient. Unlike diffusion and osmosis, it requires energy from respiration

Question 42

What 2 things does active transport allow?

Answer 42

1: mineral ions (for plant growth) to be absorbed from the soil into root hair cells 2: glucose (for cell respiration) to be absorbed into the bloodstream from the gut

Question 43

Do single-celled organisms have a large or small SA:Vol ratio?

Answer 43

Large

Question 44

What 4 things do exchange surfaces usually have?

Answer 44

1: large surface are (so lots can diffuse at once) 2: a thin membrane (for short diffusion distance) 3: an efficient blood supply (in animals) 4: ventilation (in gas exchange, in animals)

Question 45

How are leaves adapted for exchange?

Answer 45

1: flat shape 2: stomata let gases in and out

Question 46

How are the small intestines adapted for exchange?

Answer 46

1: single layer of surface cells 2: covered in villi (tiny little hairs) 3: capillary network

Question 47

How are gills adapted for exchange?

Answer 47

1: lots of gill filaments, covered in lamellae 2: lamellae have lots of capillaries 3: lamellae have a thin surface layer of cells

Question 48

How are alveoli adapted for exchange?

Answer 48

1: there are millions of alveoli 2: air moves in and out 3: alveoli have thin walls 4: capillary network