Exam qs Flashcards
Some students set up an experiment to measure the rate of water uptake by a plant cutting.
It was important to use the same plant cutting each time to make these experiments fair.
Explain why
Otherwise they may be a different size
A student investigated the effect of light on the rate of photosynthesis.
Counting the number of bubbles produced in 1 minute is not an accurate way to measure the rate of photosynthesis
Suggest two ways the method could be improved to measure the rate of photosynthesis more accurately
- the gas could be collected in a gas syringe
- Repeat several times then calculate a mean
A student investigated the effect of light intensity on the rate of photosynthesis, using an LED as a light source
The LED light source does not get hot.
Explain why it is important that the pondweed remains at a constant temperature.
As temperature affects the rate of photosynthesis because photosynthesis is controlled by enzymes.
A student investigated the effect of light intensity on the rate of photosynthesis.
Light intensity can be calculated using the inverse square law: l∝1/d2
Where l is light intensity and d is the distance of the pondweed from the light source.
The student placed the pondweed at 5, 10 and 20 cm from the light source.
Explain how light intensity changes as the distance of the pondweed from the light source is doubled.
You must include calculations in your answer
At 5cm away from the light source, light intensity will be ∝ 0.04. However, the further from the light source the pondweed is, the less the light intensity, as light intensity at 10 is ∝0.01, and at 20 l∝0.0025. Therefore, as distance doubles, light intensity is quartered
Explain why the use of peat is harmful to the environment
Do not refer to biodiversity in your answer
As the burning of peat releases carbon dioxide, as the peat absorbed carbon dioxide, increasing CO2 levels and further contributing to climate change, e.g. by increasing global warming
The rapid growth in human population means that more waste substances are released into the environment.
The release of substances into the environment can cause pollution
Describe how substances that pollute air and water could be harmful to humans and other living organisms
Part 1- Carbon dioxide / methane / greenhouse gases
Carbon dioxide / methane / greenhouse gases
- global warming/climate change / traps heat
- floods / fire / drought or ice caps melt or rise in sea level or extreme weather
- loss of habitat / food
- migration
The rapid growth in human population means that more waste substances are released into the environment.
The release of substances into the environment can cause pollution
Describe how substances that pollute air and water could be harmful to humans and other living organisms
Part 2- Acidic gas / named - e.g. SO2 / NOx
acidic gas / named - e.g. SO2 / NOx
- damage to leaves so less photosynthesis
- damage to roots or alters ions in soil (e.g. phosphates / iron)
- so less protein manufacture
- damage to lungs
- breathing difficulties / bronchitis / asthma
The rapid growth in human population means that more waste substances are released into the environment.
The release of substances into the environment can cause pollution
Describe how substances that pollute air and water could be harmful to humans and other living organisms
Part 3- Particulates / ‘soot’
particulates / ‘soot’
- cover leaves or block light
- less photosynthesis so less glucose made
- damage to lungs
- breathing difficulties / bronchitis / asthma
The rapid growth in human population means that more waste substances are released into the environment.
The release of substances into the environment can cause pollution
Describe how substances that pollute air and water could be harmful to humans and other living organisms
Part 4- sewage
sewage
- bacteria multiply
- use oxygen in respiration
- water animals cannot respire
- pathogens in water
The rapid growth in human population means that more waste substances are released into the environment.
The release of substances into the environment can cause pollution
Describe how substances that pollute air and water could be harmful to humans and other living organisms
Part 5- fertiliser
fertiliser
- algae multiply
- algae block light so plants cannot photosynthesise
- lack of oxygen for respiration - fish die
The rapid growth in human population means that more waste substances are released into the environment.
The release of substances into the environment can cause pollution
Describe how substances that pollute air and water could be harmful to humans and other living organisms
Part 6- toxic substances
toxic substances
- damages / harms cells or bioaccumulation
- interferes with metabolism - e.g. respiration / protein synthesis
The rapid growth in human population means that more waste substances are released into the environment.
The release of substances into the environment can cause pollution
Describe how substances that pollute air and water could be harmful to humans and other living organisms
Part 7- plastics
plastics
- entrap animals or causing internal damage if swallowed
A scuba diver carries an oxygen tank which contains 8 litres of compressed oxygen.
This amount of compressed oxygen is equivalent to 1000dm3 of oxygen at atmospheric pressure when the scuba diver inhales.
Assume that the breath rate of a scuba diver is 13 breaths per minute and the gas intake per breath is 3dm3.
Calculate the time it takes for the gas tank to run out of gas
Volume of gas consumed per minute = gas intake per breath x breaths per minute
Volume of gas consumed per minute = 3 x 13 = 39 dm3/min
Time to consume all = Volume of gas contained / volume of gas consumed per minute
Time to consume all = 1000 / 39 = 25.641 minutes
Round to 3 sig figs = 25.6 minutes
25.6 mins
Plasma transports many useful things throughout the circulatory system, and plasma also transports waste products. Name TWO waste products that plasma transports
Plasma transports urea and carbon dioxide
Leyland takes 63 breaths in 6 minutes.
Work out Leyland’s breathing rate
63/6 = 10.5
Leyland’s breathing rate = 10.5 breaths per min
