B1-mocks

Question 1

Describe the structure/features of a eukaryotic cell.

Answer 1

A eukaryotic cell is a cell, which contains a nucleus containing DNA of a cell

Complex
Nucleus containing DNA
Plant and animal cells

Question 2

Describe the structure/features of a prokaryotic cell

Answer 2

A prokaryotic cell is a cell with no nucleus, and DNA is found in the cytoplasm

Simpler
Singular strand of DNA and plasmids
Bacteria cells

Question 3

How are ribosomes, mitochondria and chloroplasts presented in a diagram?

Answer 3

Ribosomes-little dots
Mitochondria -Oval, long, wiggly lines
Chloroplasts-oblong, discs inside

Question 4

How is the bacteria cell wall different to a plant cell wall?

Answer 4

Bacteria cell wall is not made of cellulose and is therefore structure and protection

Question 5

Centi. Decimal divide by standard form.

Answer 5

0.01
/100
1x10^-2

Question 6

Milli-decimal divide by standard form

Answer 6

0.001
/1000
1x10^-3

Question 7

Micro. Decimal divide by standard form.

Answer 7

0.000001
/1,000,000
1x10^-6

Question 8

State, the function and parts of an animal cell

Answer 8

Nucleus-contains genetic material/DNA of a cell
Cytoplasm -where chemical reactions occur
Cell membrane -controls what enters and leaves cell and holds cell together
Mitochondria -where aerobic respiration reactions occur-release energy
Ribosome -proteinsynthesis

Question 9

State the function and parts of a plant cell

Answer 9

Nucleus- contains genetic material/DNA of a cell
Cytoplasm -what chemical reactions occur
Cell membrane -controls what enters and leaves the cell and hold cell together
Mitochondria - aerobic respiration reactions occur. Releases energy
Ribosomes -proteinsynthesis
Chloroplast-where photosynthesis occurs-contains chlorophyll to absorb light energy for photosynthesis
Permanent vacuole-contains cell sap (sugars and salt) keep sell turgid
Cell wall-made from cellulose, provide structure and support

Question 10

State the function and parts of a bacteria cell

Answer 10

Cell membrane-controls what enters and exits the cell. Keep it together.
Cytoplasm -the site of chemical reactions
Ribosomes-protein synthesis, yeah
DNA -controls the cell (squiggly lines)
Bacterial cell wall -for structure and protection
Plasmids -small loops of DNA with useful genes
Flagellum-for moving of swimming (only in some bacteria)

Question 11

What are the differences between bacteria cells and plants and animals?

Answer 11

No mitochondria or chloroplasts
No nucleus
Has a cell wall like plants, but not made of cellulose

Question 12

Define differentiation

Answer 12

Where different genes are switched on and off (produces different proteins) in each cell to change the shape and subcellular structures so they become adapted to carry out a particular function

Question 13

What is the difference between a plant cell and animal cells differentiating?

Answer 13

Plant cells can differentiate throughout the whole life
Animal cells only differentiate at an early stage, and once they are specialised very few can change-only divide by mitosis to replicate themselves.
Mitosis
fertilised embryo/stem cell ———->ball of
Differentiation
Stem cells—————-> small Fetus (all cells and tissues needed are produced)
Mitosis
———-> full sized baby

Question 14

Why do cells differentiate?

Answer 14

Cells differentiate to become specialised for its job/role/function.

Question 15

Sperm cells

Answer 15

Specialised to carry males DNA to egg cells for reproduction
Long tail, streamlined head to aid swimming
Lots of mitochondria for energy
Enzymes in head to break down membrane of egg cell

Question 16

Nerve cell

Answer 16

Specialised to transmit electrical signals from one place to another
Long axon (between tail and head) impulses carried longer distances
Lots of dendrites (extensions) connect with other cells
Many mitochondria release energy to make special chemicals-neurotransmitters

Question 17

Muscle cells

Answer 17

Specialised to contract quickly to move bones, or to squeeze and cause movement
Long-space to contract
Lots of mitochondria-release energy to contract

Question 18

Root hair cells

Answer 18

Specialised for absorbing water and minerals-at the tips of roots
Large surface area (long projections/hairs) -to increase the rate of absorption
Large permanent, vacuole-to maximise water and nutrients storage
Lots of mitochondria -to provide energy for respiration for active transport

Question 19

Xylem cells

Answer 19

Specialised to transport water and mineral ions
Lignin buildup in spirals around cell walls- to make it stronger
Hollow tube-end cell walls broken off
One way flow of sap
Have dead vessels-lack cell organelles and to ensure efficient water transport
Involved in transpirtation-loss of water from the Ariel parts of the plant. Carried water from roots to leaves where it is loss

Question 20

Phloem cells

Answer 20

Transports dissolved sugars (food) and amino acids
Made of living cells
End cell walls have pores in them (sieve plates) (allow movement of sugars)
Thin cell wall made of cellulose
Involved in translocation-sugars move from where they are produced in photosynthesis to where they are needed in the plant
Two way flow

LET
living cells
End walls
Two way flow

Question 21

Defined the term resolution

Answer 21

The ability to distinguish between two points.sharper image,higher resolution

Question 22

How do light/optical microscope work

Answer 22

Light microscope to use light and lenses to form an image of a specimen and magnify it di that we can dee the actual structure larger than life

We are able to see the nucleus and just about the size of the mitochondria at 1500 x

Question 23

What is the equation for magnification?

Answer 23

Magnification=image size /actual/realsize

I
A M

Question 24

What does the equation actually mean?

Answer 24

How many times have we multiply the actual structure to see it as that image

Question 25

Microscope required practical-using the microscope

Answer 25

. Select the lowest powered objective lens first. . Use course focus to move stage up . Look in the eyepiece use, course focus to move stage downwards if needed. . Adjust focus with fine focus until clear image . I swap with the high objective lens and re-focus.

Question 26

Microscope required practical-preparing the slides

Answer 26

. Add a drop of water onto clean slide. . Get a thin piece of any type of tissue (onion skin) . . Add this onion skin onto the slide with the drop of water. . Use a drop of iodine solution to stain specimen-add contrast to the onion skin do the structure is highlighted . Place a glass cover slip on top.-stand up right, then lower the cover slip, so no air bubbles

Question 27

Microscope required, practical-recording observations

Answer 27

. Draw with a pencil with sharp point . Draw clear unbroken line. . No shading/colouring. . Sub cellular structures should be drawn in proportion. . Include title. . Label important features.

Question 28

How do you electron microscopes work?

Answer 28

They use electrons to form an image-have a higher magnification resolution and more detail have allowed us to see inside cells in more detail and even inside mitochondria, chloroplast and bacteria

Question 29

Chromosomes and DNA

Answer 29

Nucleus contains genetic information Chromosomes are coiled up structures of DNA DNA is a long molecule that forms twisted double helix Made up of small sections called genes Different genes, control development of different characteristics Humans have 23 pairs of chromosomes -46 Females-xx male-xy

Question 30

Describe interphase

Answer 30

DNA replicates. Chromosomes replicate and grow in size. The organelles replicate.

Question 31

Describe mitosis

Answer 31

This is the actual cell division from 1 into two Chromosomes lineup in the middle of the cell Spindle fibres pull each chromosome to opposite poles

Question 32

Magnification of light, microscope

Answer 32

Magnification of the eyepiece lens x magnification of the objective lens eyepiece lens is always 10

Question 33

Why is mitosis a key process

Answer 33

It is essential for the growth and replacement of cells

Question 34

What is binary fission?

Answer 34

A type of asexual reproduction used by prokaryotic cells in order to replicate

Question 35

How fast can bacteria divide and how is this calculated

Answer 35

Bacteria can split in 2 as fast as every 20 minutes To calculate this is the formula number of bacteria x 2 ^(number of divisions)

Question 36

Describe the stages of binary fission

Answer 36

Circular DNA and plasmids replicate Cell increases in size and circular DNA strand move to opposite poles of the cell Cytoplasm divides and new cell walls begin to form Two identical daughter cells produced Very quick division in right conditions , nutrients and warm environment

Question 37

what can bacteria be grown in

Answer 37

In a liquid broth culture, or on a nutrient agar (gel) plate. culture, medium, contains carbohydrates, minerals, proteins, and vitamins.

Question 38

What does bacteria need to grow successfully?

Answer 38

Must have enough nutrients and oxygen warmth and no contaminants

Question 39

How to produce uncontaminated plates

Answer 39

Flame all instruments Flame neck of open bottles before and after Don’t place anything on the bench Disinfect services Work near a flame to produce hot air floor Petri dish must be sterilised (oven/uv light)-stops cross contamination Sterilised inoculating loop (passing thru flame)-kills unwanted microorganisms Half sealed w tape-so they have oxygen to grow Call should be incubated at 25°-So no pathogens. How are you 10th allowed for growth of harmful bacteria humans. Lower than 25 means colony can’t grow petri dish stored upside down-stop condensation from lid on agar and disrupting growth

Question 40

Investigating a photo of antibodies and bacterial growth-required practical

Answer 40

. Soak paper discs in different types of concentrations of antibiotics and place on agar plate evenly spread with bacteria . Control disc-sterilise water no death of bacteria. .Antibiotic resistant bacteria will continue to grow button on resistant die . Inhibition zone-clear area left where bacteria died . Leave played at 25° for 2 days More effective antibiotic = larger the inhibition zone Measure diameter in two places at right angles to each other and use the mean of these two and pi r squared to calculate the area

Question 41

What is a stem cell

Answer 41

Cells that have not yet undergone differentiation and are yet to be specialised Can cure diseases such as leukaemia, Parkinsons and diabetes

Question 42

What is an embryonic stem cells?

Answer 42

What type of stem cells found in embryo-capable of dividing into almost any cell type

Question 43

What is an adult stem cell?

Answer 43

A type of stem cell found in the bone marrow in adults can only differentiate into blood cells

Question 44

What is the meristem?

Answer 44

Is found in the root and shoot tips Differentiate into any type of plant cell Used to produce clones of plants quickly Used to grow more rare species Desired featured for farmers -resistant to disease

Question 45

State the advantages and disadvantages of embryonic stem cells

Answer 45

Advantage-can differentiate into any type of cell, lower chance of rejection compare to adult Disadvantage-5x more expensive to extract, highly unethical

Question 46

Disadvantages and advantages of adult stem cells

Answer 46

Advantages-more ethical, compare to embryonic as Doner can give consent, cheaper and easier to extract Disadvantages -higher rejection rate, can only differentiate into blood cells

Question 47

What is therapeutic cloning?

Answer 47

Embryo produced with same genes as patient embryo produces than harvested to obtain embryonic stem cells These grow into any cells patients need-tissue and organs Can’t be rejected as they have same genetic make up as individual

Question 48

What are the benefits and problems of using stem cells to cure diseases

Answer 48

Benefits-replace damaged body parts Unwanted embryos from fertility clinics can be used Research into the process of differentiation Problems -how to control to turn into desired cells Removal of stem cells results in disturbance of embryo Religious/ethical objections Money and time spent better elsewhere in medicine

Question 49

Defined the term diffusion

Answer 49

Diffusion is the movement of particles from an area of high concentration to an area of low concentration. Thru semipermeable membrane (only smaller molecules allowed through e.g. oxygen and glucose amino acids) Passive process -no energy required Solutions and gases -particles free to move around Eg. Oxygen and glucose diffuse into cells. Carbon dioxide / urea diffuse out of cells

Question 50

What affects the rate of diffusion?

Answer 50

Increase the concentration gradient-increase the speed of diffusion Reducing the distance particles have to travel-increase the speed of diffusion Increasing the temperature -increases speed of diffusion Increasing the surface area of membrane -increases the speed of diffusion (more particles in the past thru at once)

Question 51

Surface area to volume ratio

Answer 51

Where we divide the surface area of an organism by its volume The larger, an organism becomes the smaller the surface area to volume ratio becomes do I need specially adapted exchange surfaces and transport system to increase the rate of diffusion Single celled organisms, do you not need any exchange surface because they have a very large surface area to volume and a short distance for substances to diffuse In and out

Question 52

Define osmosis

Answer 52

The net movement of water molecules (goes both ways random) across a partially permeable membrane higher concentration (dilute as there is more water molecules) how to an area of lower concentration (more concentrated) A passive process (does not require energy) Stronger sugar concentration becomes more dilute to, even up concentration on either side Rate is affected by same factors of diffusion

Question 53

Osmosis required practical-effect of osmosis in plants issue

Answer 53

Cut up potatoes cylinders-identical Prepare a range of sucrose solutions (measured in moles per cubic decimetre) One should be pure water Measure mass of each cylinder Leave one cylinder in each beaker for equal amount of time Take out cylinders and dry them with a paper towel (to remove any excess mass) and measure mass Is cylinders have drawn in the water by osmosis -mass has increased (+ % change) Is cylinders have water drawn out-mass decreased (- % change) Calculate percentage change in mass Repeat for several cylinders Errors-dry fully, water may evaporate-repeat Dependent variable -the change in mass Independent variable -concentration of solution Control variable -volume of solution, temperature time type of sugar

Question 54

Osmosis in cells

Answer 54

Cells and dilute solution (pure water) Water moves into cells by osmosis Animal cells swell and can burst Plant cells well, but don’t burst due to cell wall Cells in solution with same concentration as cytoplasm No net movement of water in the DeSales Cells remain the same . This is my blood plasma is same concentration as blood cells cytoplasm Cells in concentrated solution (salt) Water moves out of the cell by osmosis Animal cells, shrink and shrivel up Plant cells, vacuole shrinks when cytoplasm can pull away from the cell wall

Question 55

Define active transport

Answer 55

The movement of particles from low to high concentration against a concentration gradient using energy Not passive as it requires energy from respiration Rid of active transport is affected by rate of respiration -number of mitochondria availability of oxygen. Number of carrier proteins.

Question 56

Examples of active transport

Answer 56

Plants Rehearsal Transport mineral ions against a concentration gradient from the sole in to the root hair cell. Low concentration, soil. High concentration in cell Animals Villi Lined the small intestine Transports glucose molecules against a concentration gradient from the small intestine into the blood of the equilibrium is reached low concentration in intestine, high concentration in blood

Question 57

Why do we need exchange surfaces and what are the adaptations to maximise effectiveness

Answer 57

Need exchange, surfaces For efficient, diffusion Thin membrane -short distance to diffuse Large surface area -lots of substances can diffuse Good supply of blood -maintain concentration gradient Ventilated

Question 58

Gas exchange in a lungs

Answer 58

Lungs contain millions of little air sacs-alveoli Enormous surface area 75m^2 Moist lining -dissolving gases Very thin walls -short distance Good blood supply Gases diffusing between lungs and blood in capillaries

Question 59

Villi

Answer 59

Tiny projections inside the small intestine Large surface area, so digested food is absorbed more quickly Very good blood supply Single layer of surface cells -short distance Small molecules (eg amino acids glucose) diffusing from small intestine into blood in capillaries

Question 60

Leaf

Answer 60

Carbon dioxide diffuses into air spaces in the leaf for photosynthesis Oxygen and water vapour diffuser out Flattened shape of leave increases area of exchange surface Water vapour evap from cells inside leaf-then escapes by diffusion because there’s a lot of inside to leave less of the outside Gases diffusing in and out of stomata for gas exchange in cells for respiration and photosynthesis

Question 61

Describe cytokinesis

Answer 61

The cytoplasm splits equally Two cell membrane start to form This resulted into genetically identical daughter cells being produced

Question 62

Equation for photosynthesis

Answer 62

Carbon dioxide+water——->oxygen+glucose

Question 63

Equation for aerobic respiration

Answer 63

Glucose+oxygen——->carbon dioxide+water