B17: Organisation of an ecosystem

Biomass

The mass of living material in a living organism. Measures in g/m^-2 or kg/m^-3

Substances that make up an organisms biomass

Cellulose to form cell walls

Starch for storage

Proteins, made up from amino acids using nitrates from the soil

Respiration Equation

glucose + oxygen → carbon dioxide + water

Food Chain

Producer → Primary Consumer → Secondary Consumer → Tertiary Consumer/Apex Predator

Predator-Prey Relationships

Cyclical Fluctuation

Decay Cycle (fill in the blanks)

1 - Photosynthesis

2 - Plant material eaten by consumers

3 - Mineral ions e.g nitrates go into the plant through the roots

4 - Decomposers break down dead bodies + waste materials

Carbon-containing molecules in plants, animals, the atmosphere, and faeces

Plants: Starch, Cellulose

Animals: Glycogen

Atmosphere: Carbon Dioxide

Faeces: Proteins, DNA

Water Cycle

Why is water needed in living organisms?

Turgidity in plant cells, chemical reactions (photosynthesis), chemical reactions in solution, transpiration, blood plasma to transport blood cells and platelets, sweating to maintain core body temperature.

Process of transpiration

Water is taken through the roots by osmosis and absorbed into the plant. The water then travels up the plant via the xylem tissue. It travels up into the leaves then exits the leaf through the stomata.

How and why might the water obtained from plants via respiration be different on a sunny day?

They lose more water than they gain. A plant would respire the same depending on the day. If it is sunnier, they will photosynthesise more, so the stomata will be more open, and the plant loses more water through transpiration.

Molecules that contain carbon

Fats, Carbohydrates, Nucleic acids (DNA), Proteins, CO2, Glycogen

Carbon Cycle

Decomposition is carried out by

Detritivores (woodlice, maggots, earthworms)

Decomposers (saprotrophic feeders (bacteria, fungi))

Factors that affect decay

Warm Temperature ↑

Moist conditions ↑

Presence of bacteria ↑

Lots of oxygen ↑

Cold temperature ↓

Dry conditions ↓

Lack of oxygen ↓

Lack/Lots of carbon dioxide (no effect)

How does temperature affect decomposition

Enzymes have optimum temperatures.

If it is too hot/cold, enzymes will denature.

Lower temperature means less kinetic energy, which means less collisions will happen, so less reactions will happen.

How does moisture affect decomposition

Water transports mineral ions

Water is needed for chemical reactions

Water is a crucial metabolite

How does oxygen affect decomposition

Oxygen is needed for respiration, which is necessary for digestion

Biogas Generators

Anaerobic decay produces methane gas. Biogas generators can be used to produce methane gas as a fuel for cooking heating, and burning. There are two types: Fixed dome design and Floating dome design.

Fixed Dome Design

Fixed Dome Design: Advantages and Disadvantages

Fewer metal parts

Less expensive to set up

Does not rust

Can be used by single families or communities

Gas pressure fluctuates

Less straightforward to control

Gas leakage is more likely

Production of methane is low

Floating Dome Design

Floating Dome Design: Advantages and Disadvantages

Floating dome stabilises the gas pressure

Gas production can be monitored more easily

Can be used on a larger scale

For large villages or for commercial production of methane

Expensive to set up and maintain

Requires more management

Metal construction: rusts easily