5th Form

Question 1

Advantages of greenhouses

Answer 1

consistent internal environment+additional co2 in air
Water vapour is kept inside so reduces water loss via transpiration

Question 2

2 types of fertilisers

Answer 2

Organic (animal feces) vs inorganic (chemically formed compounds to produce a specific amount of a particular ion)

Question 3

organic vs inorganic fertilisers pros and cons

Answer 3

Organic pros:
improves soil structure
greater range of minerals
cheaper
Cons:
bulkier so less practical
may contain pests
inorganic pros:
fast acting
easy to apply
cons
leads to eutrophication

Question 4

How to replace lost nitrates in soil

Answer 4

Add legumes, which have nitrogen-fixing bacteria, so convert nitrogen gas into ammonium ions. When the soil is ploughed, the ammnium is released into the soil, which is then converted to nitrates by nitrifying bacteria.

Question 5

examples of biological control agents

Answer 5

pheromones
ladybirds (natural predator)
introduce sterile males

Question 6

pesticides pros vs cons

Answer 6

reduces pest population immidiatly
cons:
need to regularly apply
chemicals can concentrate up the food chain
pests can become resistant to the chemicals

Question 7

biological control pros vs cons

Answer 7

only one inital cost
no effect on other animals in the food chain
cons:
not all population killed
takes time to reduce the pest numbers

Question 8

anaerobic respiration in yeast word and chemical

Answer 8

glucose to ethanol + co2
C6H12O6 to 2C2H5OH + “Co2

Question 9

hydrogen carbonate indicator for co2

Answer 9

orange to yellow

Question 10

experiment for anaerobic respiration in yeast

Answer 10

1. Dissolve sugar in previously boiled water
2. Add yeast and stir
   3.Add a layer of vegetable oil
3. Connect via a bung and gas delivery tube to a second boiling tube containing limewater

Question 11

bacteria used to make yogurt

Answer 11

lactobactillus bulgaricus

Question 12

key steps for making yogurt

Answer 12

1. Equipment is sterilised
2. Milk pasteurised by heating
3. lactobactillus bulgaricus is added to the milk and left at 46c for 4 hours

Question 13

why is lactobactillus good

Answer 13

produces latic acid which lowers the Ph and therefore coagulate the mixture, giing yogurt its texture

Question 14

why must fish species be seperated in fish farming

Answer 14

interspecficic competition + predation

Question 15

problems with too many fish in a farmed pond + solutio

Answer 15

intraspecifc competion
rapid pathogenous spread
solution:
add antibiotics or antifungals/chemicals

Question 16

problems with fish farming

Answer 16

fish may escape and upset ecosystem
fish may introduce pathogens
fish waste/ excess food can cause eutrophication

Question 17

leaching

Answer 17

when trees are cut down, water runs off the soil instead of being absorbed by the roots. This means
a) there is a loss of minerals in the soil as they dissolve with the water
b) eutrophication can occur
c) the nutrient rich layer of topsoil is eroded

Question 18

cause and effect of sulphur dioxide

Answer 18

released from cars and factories. They react with water in the atmosphere to create dilute acids. Can decreae the Ph of rivers and lakes, resulting in enzmes in animals being unable to react, creating death of organism. Also increases the dissolution of metal ions in soil, poisoning fish

Question 19

steps of eutrophication

Answer 19

excess nitrates are abosrbed by algae
algae multiplies rapidly, so plants underneath die
bacteria feeds on dead algae and respires
fish die from lack of oxygen

Question 20

how does rna differ from DNA

Answer 20

1. RNA is single stranded (vs double stranded)
2. RNA has a sugar called ribose (deoxyribose)
3. RNA has base Uracil while DNA has base thymine

Question 21

gene

Answer 21

a lengh of DNA which codes for a protein