Bio Alt to Prac

Question 1

for diagrams ensure

Answer 1

• use at least half of space
• NO sketching
• labels touch related obj. RULER used & best horizontal
• have detail

Question 2

drawing diagrams [IMPORTANT]

Answer 2

• use only a single, clean, bold line to outline structures of organism - NO SHADING OR SKETCHING
• label lines TOUCH organism
• use more than half of given space
• include all outlines, structures, patterns

Question 3

iv

Answer 3

variable in investigation we are changing/manipulating

Question 4

dv

Answer 4

variable in investigation we’re measuring

Question 5

cv

e.g. water, soil, temp, day/night time

Answer 5

variable/s in investigation we are keeping constant

note: all variable that could impact the dependent variable should be controlled except iv

Question 6

continuous data

Answer 6

• does not fall into distinct categories
  -can have a spectrum of values

e.g. height, weight, skin colour, cm a plant grows

Question 7

discontinuous data

Answer 7

• falls into distinct categories with no intermediates

e.g. eye colour, occupation, taking transport, fav ff chain

Question 8

identifying errors (mistakes that decrease accuracy & reliability of data)

• common:

Answer 8

• inaccurate measurement of dependent or independent variable; could be through using incorrect equipment or parallax error

📌 failing to keep controlled variables constant (temp, levels)

📌 failing to do repeats

• contaminated equipment (sterilising swab before og sample)

Question 9

planning scientific investigations -

MUST:

Answer 9

-include units for everything
-state IV
- state DV
-state at least 3 CVs. EVERYTHING that could impact DV
-give DETAILED, NUMBERED, PRECISE METHOD. explain EVERYTHING you must do.
- mention doing REPEATS to increase accuracy and reliability of data

Question 10

drawing tables

Answer 10

ensure:

-use a ruler - make NEAT & TIDY
- all variables/measurements have a heading that includes units
- include units for every cell [JIC]

Question 11

drawing graphs:

line, bar [GAPS, 1 con 1 discon], histogram [NO GAPS BTWN, both only con]

Answer 11

• a title
• x and y axis labels including units
  -even scale
  -plot points in correct position
  -MUST use at least half of space given

Question 12

magnification

Answer 12

_ I
AΔM

Question 13

table

Answer 13

names of 2 beakers/test tubes A/B on left column. nth above

main top heading Change of Temperature Per Minute (℃)

Below it 5 columns from ZERO MINUTES [values given in ques] to 5 min as asked. all labelled with “min” at end

“appropriate rounding” => 1 d.p.

Question 14

connect to previous ques / actually connect to experiment and use appropriate terminology/words - scientific.

Answer 14

e.g.,

The larger the penguin the lower the RATE of heat loss

OR, the larger penguin loses heat more slowly

Question 15

with exps where objects rep animals etc., don’t state IV as the representative thing but the LITERAL one used in exp.

Answer 15

e.g.,

❌ “type of penguin”

✅ size of the container

Question 16

CVs [1] - examples in MS

Answer 16

• starting temperature of the water;
• height of water on each container ;
  -temperature of environment / surroundings ;

Question 17

Plan an investigation to determine the effect of temperature on the rate of diffusion in model cells. [6]

[Agar jelly cubes are colourless and can be stained pink with an indicator. When placed in an acid solution, the acid diffuses into the agar jelly cubes and the pink colour starts to disappear. When the acid has reached the centre of the agar jelly cube, the agar is completely colourless]

Answer 17

any 6 of these 7:

• the independent variable is at least two different temperatures
  -the dependent variable is the time taken for the cube to become completely colourless
  -MAX 3 OF: variables kept constant should be same size agar cubes, volume of acid, pH of acid, same type of indicator, and using the same type of acid - use hydrochloric acid
  -repeat investigation two more times
  -a relevant safely precaution is googles. also cut away from hand

Question 18

OTHER MARKS- harder to get. DETAILING A METHOD

WORTH 3 MARKS. half of marks but must touch on:

method of maintaining different temperatures ;
method of cutting agar cubes ;
enough acid to cover cubes / AW

Answer 18

• in this investigation three different temperatures of 30℃, 40℃, and 50℃ used.

Cut the pink agar jelly cube into dimensions 1cm x 1cm x 1cm using a knife.

Add the slices of cubes into the acid, enough acid to cover cubes, which is placed on a THERMOSTATICALLY CONTROLLED WATER BATH. Then record the time taken for the cube to become colourless.

Question 19

State a conclusion for the results of this investigation.

more bubbles in B (yeast suspension
and glucose solution)
less in A (0.1mol/dm^3 glucose solution)

Answer 19

at higher (glucose) concentrations (yeast) respires at a higher rate