Download S1 Photosynthesis and Biodiversity WYSK

What You Should Know:
Photosynthesis and Biodiversity
Photosynthesis:
Write a word equation for the process of photosynthesis and state that it is carried out
in green plants.
Light
Carbon Dioxide + Water
→
Glucose + Oxygen
Chlorophyll
Water is taken in at the roots of the plant. Carbon dioxide is taken into the leaves of
the plant through tiny holes called stomata.
The green coloured chemical chlorophyll can absorb the energy of the sun light and
uses this energy to make food molecules.
Glucose is produced during photosynthesis and is converted into starch (which can be
stored in the plant). Oxygen is released as a by-product.
Testing a green leaf for starch:
1.
2.
3.
Boil the leaf in water to break open the cells.
Heat the leaf in alcohol in a test tube in the hot water to take the green
coloured chlorophyll out of the leaf.
Rinse the leaf and drop some iodine onto the leaf. If the iodine turns black this
shows starch is present.
Green plants depend on photosynthesis to make the food that gives them energy for
life. Animals also depend on photosynthesis because they either eat plants or eat other
animals which eat plants. Animals also depend on the oxygen that plants make.
Biotic and Abiotic factors
All living things are affected by things in the environment that can have a positive of
negative affect on their survival chances. These are called biotic or abiotic factors.
Biotic factors are living factors present in an ecosystem, which can affect a living
organism’s survival. These include availability and competition for food, number of
predators and diseases.
Abiotic factors are non-living factors present in an ecosystem, which can affect
living organisms’ distribution and survival. These include light intensity, temperature,
moisture, pH, wind speed and oxygen content.
Light intensity is measured by a light meter. Ensure no shadows are cast over the
meter during measuring.
Moisture is measured by a moisture meter. Ensure the probe is wiped clean between
uses.
Temperature is measured by a thermometer. Ensure thermometer is given time to
settle before reading.
The effect of Abiotic factors on organism distribution
Some plants need high levels of light to grow and can not grow in shaded areas
Other plants grow best in shaded area because there is less competition.
Some organisms can not survive in acidic conditions.
Some organisms like woodlice, need to live in moist conditions
Biodiversity
Biodiversity is a measure of the the variety of life on Earth and the essential
interdependence of all living things
Some habitats are more biodiverse than others e.g. the Amazon rainforest is more
biodiverse than the Sahara desert.
Scientists have identified more than 2 million species. Tens of millions remain
unknown
The tremendous variety of life on Earth is made possible by complex interactions
among all living things including microscopic species like bacteria, algae and mites.
Sampling
We can measure how much biodiversity there is in a habitat by counting both the
number of different species in the environment and how many individual animals or
plant there are of each species. We do this by sampling. There are many ways of
sampling in different habitats. Two examples are quadrats and pitfall traps:
Quadrats
Quadrats are squares used to estimate numbers of small ground living plants in an
area.
To find the how many plants of one (i.e. daisies) type are in a field. A quadrat is
placed at several random sites in the field. We then count the number of squares that
daisies are in. Not the individual daisies
Pitfall Traps
Soil level
Beaker
Pitfall traps are generally very simple traps dug into the earth. Pitfall traps catch small
organisms, which are active on the ground. Camouflage such as leaves are used to
cover the top of the cup/beaker at the soil surface allowing the organisms to fall into
the trap unsuspectingly.