b1 cell biology

Question 1

differences between prokaryotes and eukaryotes

Answer 1

1) prokaryotes have a single loop of DNA called plasmids, whereas eukaryotes have a nucleus
2) prokaryotes are much smaller in size
3) prokaryotes have a bacterial cell wall, made from peptidogyclan
4) prokaryotes dont have chloroplasts or mitochondria

Question 2

what do animal cells contain?

Answer 2

nucleus
mitochondria
ribosomes
cytopasm
cell membrane

Question 3

what do plant cells contain?

Answer 3

nucleus
rigid cell wall
cell membrane
mitochondria
ribosomes
cytoplasm
vacuole
chloroplasts

Question 4

function of nucleus?

Answer 4

controls genetic material and controls the activities of the cell

Question 5

function of mitochondria?

Answer 5

where most of the reactions for aerobic respiration take place and providing energy for the rest of the cell

Question 6

function of ribosomes?

Answer 6

where protein synthesis takes place, making proteins

Question 7

function of the cell membrane?

Answer 7

hold the cell together and controls what goes in and out of the cell

Question 8

function of the cytoplasm?

Answer 8

gel-like substance where most of the chemical reactions take place. also contains enzymes that control these chemical reactions

Question 9

function of cell wall?

Answer 9

made of cellulose and supports the cell and strengthens it

Question 10

function of vacuole?

Answer 10

contains cell sap, a weak solution of sugar and salts

Question 11

function of chloroplasts?

Answer 11

where photosynthesis takes place, making food for the plant. also contains chlorophyll which absorb light energy

Question 12

orders of magnitude?

Answer 12

10x bigger= 10^1
100x bigger= 10^2
1000x bigger= 10^3
10x smaller= 10^-1

Question 13

how to estimate the area of a sub-cellular structure?

Answer 13

treat it as as a regular object and use the equation:
area= length x width

Question 14

what is a tissue?

Answer 14

a layer of cells with a similar function

Question 15

what is an organ?

Answer 15

a group of tissues working together to perform a similar function

Question 16

what is an organ system?

Answer 16

a group of organs working together to perform a vital function

Question 17

how are sperm cells adapted for its function?

Answer 17

1) long tail so the sperm can move to the ovum.
2) the acrosome is packed with digestive enzymes to eat through the top layer of the ovum
3) full of mitochondria to provide energy for the sperm cell to swim longer distances

Question 18

how are nerve cells adapted for function?

Answer 18

1) long axons, enabling impulses to be carried through long distances
2) a lot of dendrites to branch connections and form other nerve cells
3) a lot of mitochondrian to supply energy to make neurotransmitters
4) myelin sheath to prevent electrical current from exiting the axon and to maximise electrical current transmission

Question 19

how are muscle cells adapted for function?

Answer 19

1) proteins called myosin and actin which slide over one another so the muscles can contract
2) a lot of mitochondria for re respiration and contraction
3) contains glycogen for respiration

Question 20

how are root hair cells adapted for its function?

Answer 20

1) large surface area, due to roots, for more osmosis
2) mitochondria to provide energy for active transport of minerals

Question 21

how are xylem cells adapted for its function?

Answer 21

1) the lignin which causes the cell to die, they become hollow and are joined end-to-end to form a long tube that the mineral ions can flow through.
2) the lignin is deposited in spirals so the cells can withstand the water pressure

Question 22

how are phloem cells adapted for its function?

Answer 22

1) cell walls form sieve plates when they break down, allowing movement of substances from cell-to-cell

Question 23

what happens as an organism develops?

Answer 23

cells in the body differentiate to become different cells and to complete different functions

Question 24

when do animal cells usually differentiate?

Answer 24

at an early stage

Question 25

when do plant cells usually differentiate?

Answer 25

at any stage of their life

Question 26

how have microscopy techniques developed overtime?

Answer 26

1) light microscopes use light and lenses to observe individual cells and large sub-cellular structures 2) electron microscopes use electrons to form an image. it provides a higher magnification and resolution.

Question 27

how has the electron microscope increased understanding in sub-cellular structures?

Answer 27

because the electron microscope has a much higher magnification and resolution,this means that we can study cells in much more finer details, therefore increasing scientists understanding of sub-cellular structures

Question 28

equation for magnification?

Answer 28

size of image// size of actual object

Question 29

how can bacterial cells divide and many times can they divide?

Answer 29

1) binary fission 2) once every 20 minutes

Question 30

methods in which bacteria can be grown?

Answer 30

1) nutrient broth solution 2) grown s colonies on agar gel plates

Question 31

why are uncontaminated cultures required?

Answer 31

investigating disinfectants and antibiotics

Question 32

method of culturing?

Answer 32

1) sterilise petri dish using an autoclave 2) sterilise inoculating hoops by passing it through a fire 3) seal the lid of the petri dish (not completely) with tape 4) store petri dish upside down 5) incubate at 25 degrees

Question 33

why should you sterilise the petri dish?

Answer 33

to prevent contamination with other (unwanted) micro-organisms. as they may compete with the desired bacteria for space and nutrients and xreate a new pathogen

Question 34

why should you sterilise inoculating loop with a fire?

Answer 34

to kill unwanted organisms

Question 35

why should u seal the lid (not completely) with tape?

Answer 35

sealing it stops air borne micro-organisms from entering and contaminating the culture but sealing it all the way could lead to harmful anaerobic bacteria growing

Question 36

why should the petri dish be stored upside down?

Answer 36

to prevent condensation from landing on the agar surface, disrupting growth

Question 37

why should u incubate your culture at 25 degrees?

Answer 37

to prevent bacteria to grow at bodily temperatures which means they can enter a human and manage to survive, before causing potential harm

Question 38

how to calculate cross- sectional colonies of bacteria?

Answer 38

pi x radius^2

Question 39

what does the nucleus of an animal cell contain?

Answer 39

contains chromosomes made of DNA molecules. Each chromosome carries a large number of genes

Question 40

how are chromosomes in the body found?

Answer 40

in pairs

Question 41

explain mitosis cycle?

Answer 41

1) sub-cellular structures are replicated and pulled to each end of the cell 2) chromosomes line up at the centre of the cell and cell fibres pull them apart. the chromosomes go to opposite ends of the cell 3) membranes form around eat set of the chromosomes, becoming the nuclei of the cell 4) cytoplasm and membrane divide, creating 2 daughter cells

Question 42

why is mitosis important?

Answer 42

important in the growth and development of multicellular organisms

Question 43

what are stem cells?

Answer 43

A stem cell is an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation

Question 44

what are the functions of stem cells in embryos?

Answer 44

to repair, or regenerate tissue and cells

Question 45

what is the function of stem cells in adults?

Answer 45

repair damaged tissue and regeneration

Question 46

what is the function of meristem cells?

Answer 46

a source of new cells to grow or replace specialised tissues

Question 47

what types of cells can embryos make?

Answer 47

embryos can become almost any type of cell

Question 48

what type of cells can bone marrow make?

Answer 48

mainly blood cells

Question 49

what type of cells can meristem make?

Answer 49

any type of plant cell

Question 50

what types of conditions could stem cells cure?

Answer 50

1) paralysis 2) amputees 3) diabetes

Question 51

what happens in therapeutic cloning?

Answer 51

and embryo is produced with the same genes as the patient. therefore the embryo won't be rejected by the patient's body. this is effective with the treatment

Question 52

what are the problems with the use of stem cells?

Answer 52

1) could transfer a viral infection 2) ethical reasons as some people may view the embryo as potential life

Question 53

how can stem cells from meristems in plants can be used to produce clones of plants quickly and economically?

Answer 53

1) Rare species can be cloned to protect from extinction. 2) Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers.

Question 54

what is diffusion?

Answer 54

the movement of particles in a solution or gas. from a high conc to a low conc. moving down the conc gradient. no energy required

Question 55

examples of substances in the body that are transported via diffusion?

Answer 55

1) oxygen for gas exchange 2) carbon dioxide for gas exchange 3) waste product of urea from cells into the blood plasma for excretion from kidneys

Question 56

factors that affect the rate of diffusion?

Answer 56

1) concentration 2) temperature 3) surface are of membrane

Question 57

how does an increase in concentration affect the rate of diffusion?

Answer 57

it increases the rate of diffusion as it increases the concentration gradient

Question 58

how does the increase in temperature affect the rate of diffusion?

Answer 58

it increases the rate of diffusion as the heat increases the Ke of the particles, there they move around faster

Question 59

how does the increase in surface area affect the rate of diffusion?

Answer 59

increases the rate of diffusion as there more space for the particles to diffuse past, therefore more particles will diffuse

Question 60

what is osmosis?

Answer 60

the movement of water from a dilute solution to a concentrated solution through a partially permeable membrane. moving down the conc gradient. no energy required

Question 61

what is active transport?

Answer 61

the movement of substances from a more dilute solution to a more concentrated solution (against a concentration gradient). This requires energy from respiration

Question 62

what is the importance of active transport in plants?

Answer 62

allows mineral ions to be absorbed into plant root hair cells from very dilute solutions in the soil. plants require ions for healthy growth

Question 63

what is the importance of active transport in humans?

Answer 63

allows sugar molecules to be absorbed from the lower concentrations in the gut into the blood which has a higher concentration. sugar molecules are used for respiration

Question 64

why are mineral ions important for plant growth?

Answer 64

1) nitrate- used for the production of animo acids which form protein 2) magnesium- used for the production of chlorophyll which absorbs light energy for photosynthesis