biology b1

Question 1

what is photosynthesis?

Answer 1

• making food for plants
• endothermic reaction
• carbon dioxide + water = glucose + oxygen

Question 2

what does chlorophyll do?

Answer 2

absorb light energy
contains green pigment

Question 3

photosynthesis is divided into what?

Answer 3

two stages

Question 4

what happens to the glucose produced in photosynthesis?

Answer 4

• when it is not needed, it is converted to starch
• respiration
• fats and oils
• proteins (growth and repair)
• sucrose (stored in fruit)
• cellulose ( to form cell walls)

Question 5

how to test starch for plants?

Answer 5

• put the leaf in a beaker of boiling water to kill it
• place leaf into boiling tube of ethanol to remove chlorophyll
• wash leaf with water to remove ethanol
• add few drops of iodine solution

if starch is present, iodine will turn blue-black

Question 6

what are limiting factors of photosynthesis?

Answer 6

light intensity
carbon dioxide
temperature
(affect rate of photosynthesis)

Question 7

what formula is used to calculate rate of photosynthesis?

Answer 7

rate = 1/t
t = time for measurement to occur

Question 8

how does light intensity affect the rate of photosynthesis?

Answer 8

the higher the light intensity, the faster the rate of photosynthesis
photosynthesis stops if there is no light as the stomata closes

Question 9

how does carbon dioxide affect the rate of photosynthesis?

Answer 9

as it is one of the reactants for photosynthesis, the greater the CO2 concentration, the faster the rate of reaction

Question 10

how does temperature affect the rate of photosynthesis?

Answer 10

the higher the temperature, the faster the reaction occurs however if temperature is too high, the enzymes will denature as active site changed shape and reaction stops

Question 11

how can you investigate the rate of photosynthesis?

Answer 11

using pondweed
the volume of oxygen given off per min is the measure of photosynthesis

Question 12

how to study effect of photosynthesis by light intensity?

Answer 12

place a light source (lamp) at different distances from the pondweed (that’s in water)

count number of bubbles in one min and repeat 5 times

Question 13

what is the inverse square law / how to calculate relative light intensity?

Answer 13

RLI = 1 / (distance from light source)squared

Question 14

how to study effect of photosynthesis by CO2 concentration?

Answer 14

add different masses of potassium hydrogen carbonate powder to the water
this releases CO2 into the atmosphere

Question 15

how to study effect of photosynthesis by temperature?

Answer 15

place the apparatus in water baths at different temperature and count number of oxygen bubbles produced

Question 16

What happens when increasing a limiting factor no longer makes a difference to the rate of photosynthesis?

Answer 16

One of the other factors is now in short supply, becoming the limiting factor.

Question 17

True or False: Increasing light intensity will always increase the rate of photosynthesis.

Answer 17

False

There are conditions where other factors limit the rate of photosynthesis despite increased light intensity.

Question 18

What is a limiting factor in the context of photosynthesis?

Answer 18

A factor that restricts the rate of photosynthesis when it is in short supply.

Question 19

what does the nucleus do?

Answer 19

• controls the activities of the cell
• contains genetic material arranged as chromosomes

Question 20

what does the mitochondria do?

Answer 20

where respiration happens

Question 21

what does the cell membrane do?

Answer 21

• barrier that controls what substances goes in and out of cell
• also contain receptor molecules

Question 22

what does the cytoplasm do?

Answer 22

a ‘jelly-like’ substance where chemical reactions occur

Question 23

what do ribosomes do?

Answer 23

the site of protein synthesis

Question 24

what extra sub cellular structures do plant cells contain?

Answer 24

cell wall
vacuole
chloroplasts

Question 25

what do chloroplasts do?

Answer 25

contain chlorophyll which is a green pigment chlorophyll transfers light energy to the plant used in photosynthesis

Question 26

what does the vacuole do?

Answer 26

• full of cell sap • helps keep the cell rigid and supports the plant, keeping it upright

Question 27

what does the cell wall do?

Answer 27

• made of cellulose (a tough fibre) • surrounds the cell • makes wall rigid and supports the cell

Question 28

how do plant cells remain rigid?

Answer 28

it contains a vacuole which is full of cell sap also has a cell wall which is made from tough fibres

Question 29

what are bacteria?

Answer 29

the smallest living organisms and are unicellular

Question 30

what is the difference between prokaryotic and eukaryotic cells?

Answer 30

in eukaryotic cells, genetic material is in the nucleus in prokaryotic cells, genetic material floats freely in the cytoplasm prokaryotic cells contain flagella’s and also contain plasmids

Question 31

how to observe cells through a light microscope?

Answer 31

• move stage to its lowest position • select the objective lens with lowest magnification • place slide on stage • raise stage to its highest position • lower stage slowly using coarse focus knob until object is seen • turn the fine focus knob slowly until object is clear • switch to higher magnification to see cells in more detail

Question 32

how does a light microscope work?

Answer 32

microscope passes light through a mirror then through the objective lens and eyepiece lens which the lenses magnify the object when viewed through eyepiece

Question 33

how to calculate magnification?

Answer 33

total magnification = eyepiece lens magnification x objective lens magnification

Question 34

why stain the cells?

Answer 34

most cells are colourless so it’s stained to make it easier to observe

Question 35

how to apply stain on cells:

Answer 35

• place cells on glass slide • add one drop of stain • place a coverslip on top • tap coverslip gently with pencil to remove air bubbles

Question 36

how do electron microscopes work?

Answer 36

they use electrons instead of light to produce an image

Question 37

what are two types of electron microscopes?

Answer 37

Transmission electron microscopes (TEM) Scanning electron microscopes (SEM)

Question 38

what are the differences between light and electron microscopes?

Answer 38

light microscopes are cheaper, easier to operate, smaller, simpler, and have lower resolution electron microscopes are more expensive, harder to operate, larger, more complex, higher resolution

Question 39

where is the dna in cells?

Answer 39

nucleus

Question 40

what are chromosomes?

Answer 40

each long molecule of dna

Question 41

how many chromosomes do humans have?

Answer 41

46

Question 42

what are genes?

Answer 42

short sections of the dna that codes for a characteristic

Question 43

what is the structure of DNA?

Answer 43

it is made up of two strands which are joined together by bases. the strands are joined together and twisted which forms a double helix

Question 44

what is a double helix?

Answer 44

made of bases that are joined together and twisted

Question 45

what are the complementary base pairings?

Answer 45

A - T C - G

Question 46

what are nucleotides?

Answer 46

small units made from DNA

Question 47

is DNA a monomer or polymer?

Answer 47

polymer

Question 48

what is each nucleotide made from?

Answer 48

sugar base (A, T, C or G) phosphate

Question 49

why is DNA a polymer?

Answer 49

it’s made from nucleotides which are joined together

Question 50

what are enzymes?

Answer 50

biological catalysts which are made of protein speeds up rate of reaction

Question 51

what are enzymes made up from?

Answer 51

long chains of amino acids which are folded together to form a specific shape

Question 52

what is the active site?

Answer 52

the empty space that the substrate binds to the enzyme

Question 53

what is the substrate?

Answer 53

molecule that binds to the enzyme

Question 54

what is the hypothesis called of the way enzymes work?

Answer 54

lock and key method

Question 55

what factors affect enzymes?

Answer 55

temperature pH concentration

Question 56

what is the optimum temperature?

Answer 56

where the reaction works as fast as possible where the enzyme works best

Question 57

what is the effect on temperature in an enzymic reaction?

Answer 57

the higher the temperature, the faster the reaction until it reaches its optimum and denatures

Question 58

what happens when an enzyme denatures?

Answer 58

active site changes shape so the substrate can no longer bind and return to its original shape

Question 59

what does a change in pH do to enzymes?

Answer 59

it affects the interactions between amino acids in a chain which may make the enzyme unfold

Question 60

what does a change in concentration do to enzymes?

Answer 60

the higher the substrate concentration, the faster the rate of reaction when substrates are used up, reaction will stop

Question 61

what do foods rich in carbohydrates and fats do?

Answer 61

provides energy to move and stay alive

Question 62

what do foods rich in protein do?

Answer 62

growth and repair of body tissues

Question 63

what is the metabolic rate?

Answer 63

speed at which body converts food into energy

Question 64

what are carbohydrates?

Answer 64

polymers that are made from sugars