past paper

Question 1

explain how PCB’s led to the death of the killer whale

Answer 1

as the pcbs accumulated in the whales fat and they then received a toxic dose
bioaccumulation is where harmful chemicals are passes along the food chain (animal at highest receives toxic dose)

Question 2

apart from death causing, describe another effect of pcbs on killer whales in uk waters and how are some still present after being banned

Answer 2

it can cause infertility as no offspring are born and as they cannot be broken down

Question 3

uses of water in plants

Answer 3

photosynthesis, help keep cell turgid as it fills cell vacuoles, pushes against cell walls and prevents them from becoming flacid or wilting and transport minerals

Question 4

in transpiration name things that can be kept constant

Answer 4

light intensity, light distance, temperature, humidity, surface area of leaves

Question 5

how can confidence be improved in results

Answer 5

repeat experiment

Question 6

explain why a potometer cannot be used to study transport of sugars in a plant

Answer 6

only measures transpiration and sugars are not transported by the xylem

Question 7

label 3 parts of onion cells

Answer 7

nucleus, cell wall and cytoplasm

Question 8

suggest an explanation for the shape of graph one between 400-800 ppm

Answer 8

light/temperature became limiting factors

Question 9

state how scientists increased the validity of their conclusions about the global changes to CO2 concentrations in the atmosphere

Answer 9

many experiments carried out worldwide

Question 10

suggest why its importany that scientists use FACE experiments on plant growth to study effects of increasing CO2 concentrations instead of similar experiments in greenhouses

Answer 10

plants may grow differently outdoors compared to greenhouses or conditions in greenhouses are controlled but conditions outside arent

Question 11

describe how the bell and jar model could be used to demonstrate inspiration

Answer 11

the rubber sheet is pulled down, volume decreases, pressure increases, air is drawn into balloons

Question 12

function of pancreas

Answer 12

secretes protease, lipase and carbohydrases to the small intestine

Question 13

how does the stoma and cuticle involved in the control of waterloss from a leaf

Answer 13

stoma open and close to control the waterloss and cuticle is waterproof to reduce waterloss from evaporation