Energy and ecosystems - Yr 2

Question 1

Biomass

Answer 1

The total mass of living material in a specific area at a given time. Usually measured in gm-2. Fresh mass is quite easy to assess, but varies depending on the water content. Measuring dry mass overcomes this problem but the organism must be killed, it is usually only a small sample and may not be representative.

Question 2

Calorimetry

Answer 2

The chemical energy store in a dry mass can be estimated using this technique. When a sample of dry material is weighed and then burnt in pure oxygen within a sealed container (bomb). The bomb is surrounded by a water bath and the heat of combustion causes a temperature rise. This can be used to work out the energy released from the mass of burnt biomass.

Question 3

Producer

Answer 3

Photosynthetic organism that manufacture organic substances using light energy, water, carbon dioxide and mineral ions.

Question 4

Consumer

Answer 4

An organism that obtains its energy by feeding on (consuming) other organisms. Primary consumers eat producers. Secondary consumers eat primary consumers. Tertiary consumers eat secondary consumers.

Question 5

Extracellular digestion

Answer 5

When saprobionts release enzymes externally which break down large biological molecules into smaller ones which are then absorbed by digestion or active transport.

Question 6

Trophic level

Answer 6

Each stage in a food chain

Question 7

GPP

Answer 7

Gross primary production which is the total quantity of the chemical energy store in plant biomass, in a given time. Plants use 20-50% of this energy in respiration.

Question 8

NPP

Answer 8

Gross primary production – respiratory losses. The chemical energy store which is left when these losses to respiration have been taken into account. This is available for plant growth and reproduction and available to other trophic levels in the ecosystem (such as consumers and decomposers).

Question 9

Respiratory losses

Answer 9

Taken away from GPP to calculate NPP.

Question 10

Food chain

Answer 10

Describes a feeding relationship in which the producers are eaten by primary consumers, which are eaten by secondary consumers, which are then eaten by tertiary consumers. These could then be eaten by quarternary consumers. Each stage is referred to a trophic level.

Question 11

Food web

Answer 11

How food chains link together in a habitat to form a food web.

Question 12

Pyramid of Number

Answer 12

A pyramid drawn with bar lengths proportional to the numbers of organisms present

Question 13

Pyramid of Biomass

Answer 13

A pyramid drawn with bar lengths proportional to the mass of plants/animals

Question 14

Pyramid of Energy

Answer 14

A pyramid drawn with bar lengths proportional to the energy stored in organisms

Question 15

Productivity

Answer 15

The rate of generation of biomass in an ecosystem. Usually measured in units of mass per area put unit time (gm-2y-1). Farming practices try to improve this by increasing yields by increasing the efficiency of energy transfer along the food chains which produce our food.

Question 16

Intensive farming

Answer 16

A type of farming which uses processes, such as using confined spaces to restrict movement, keeping the environment warm and excluding predators, to try and make energy conversion more efficient by ensuring that as much energy from respiration as possible goes into growth rather than other activities or other organisms.

Question 17

Percentage Efficiency

Answer 17

Can be calculated by dividing the energy available after the transfer by energy available before the transfer x 100.

Question 18

Energy Transfer

Answer 18

(Energy available after the transfer / energy available before the transfer) x 100

Question 19

Biological Control

Answer 19

Controlling pests by introducing predators

Question 20

Selective Breeding

Answer 20

Breeding of organisms by human selection of parents for certain characteristics

Question 21

Ecosystem

Answer 21

All the living and non-living components of a particular area.

Question 22

Saprobiontic microorganism

Answer 22

Also known as saprophyte – an organism that obtains its food from the dead or decaying remains (detritus) of other organisms.

Question 23

Detritrivores

Answer 23

Organisms that help saprophytes do their job. They feed on pieces of dead and decaying material and finely break it up increasing its surface area.

Question 24

Decomposer

Answer 24

Any organism which breaks down organic matter. Include saprophytes and detritivores.

Question 25

Nitrogen cycle

Answer 25

Four main stages: ammonification, nitrification, nitrogen fixation and denitrification. This is because all living organisms require a source of nitrogen from which to manufacture proteins, nucleic acids and other nitrogen-containing compounds.

Question 26

Nitrogen fixation

Answer 26

Conversion of nitrogen gas into nitrogen-containing compounds. Carried out by free-living nitrogen fixing bacteria and mutualistic nitrogen-fixing bacteria which live in nodules on the roots of plants such as peas and beans. It can also be carried out industrially and occurs naturally when lightning passes through the atmosphere.

Question 27

Nitrogen fixing bacteria

Answer 27

Carry out the process of nitrogen fixation. Can be free-living or mutualistic bacteria.

Question 28

Ammonification

Answer 28

Production of ammonia from organic nitrogen-containing compounds e.g. urea and proteins. Saprobiontic microorganisms feed on faeces and dead organisms materials, releasing ammonia which then forms ammonium ions in the soil.

Question 29

Nitrification

Answer 29

Carried out by free-living nitrifying bacteria. Some convert ammonia into nitrites and some convert nitrites into nitrates using oxidation reactions which release energy. Good drainage and ploughing prevents air spaces from being filled with water and allows nitrification to continue.

Question 30

Denitrification

Answer 30

Carried out by anaerobic denitrifying bacteria which convert of soil nitrates into nitrogen gas.

Question 31

Phosphorus cycle

Answer 31

Enables the cycling of phosphorous which is an important biological element as it is a component of ATP, phospholipids and nucleic acids. There is no gaseous phase in the phosphorous cycle.

Question 32

Phosphate

Answer 32

PO43- ions are how phosphorous exists mostly in the form of sedimentary rock deposits.

Question 33

Weathering

Answer 33

How rocks are worn away - how phosphate ions in wastes and remains e.g. guano, bones and shells and in rocks are released into oceans, lakes and soils as dissolved phosphate ions.

Question 34

Mycorrhizae

Answer 34

Mutualistic association between certain types of fungi and the vast majority of plants. The fungi act like extensions of the plant’s root system and increase the surface area for absorption of water and minerals. The fungi receives organic compounds such as sugars and amino acids from the plant. The mycorrhiza act like a sponge and so holds water and minerals in the neighbourhood of the roots, enabling the plant to better resist drought and take up inorganic ions more readily. They improve the uptake of relatively scarce ions such as phosphate ions.

Question 35

Guano

Answer 35

The excrement of seabirds and bats.

Question 36

Symbiotic

Answer 36

When two species live in close proximity. Mutualistic is a type of symbiotic relationship where the relationship is mutually beneficial for two organisms.

Question 37

Fertiliser

Answer 37

Using these replenishes mineral ions, especially nitrates. They are necessary to improve productivity because in agriculture crops are harvested and mineral ions are not returned to the soil by decomposition by microorganisms, like would normally happen. They increase productivity because they provide minerals such as nitrogen for plants to build proteins, ATP and DNA nucleotides.

Question 38

Inorganic

Answer 38

Type of fertiliser which are mined from rocks and deposits and then converted into different forms and blended together to give the appropriate balance of minerals for a particular crop. Contain nitrogen, phosphorous and potassium.

Question 39

Organic

Answer 39

Type of fertiliser which consist of the dead and decaying remains of plants and animals as well as animal wastes such as manure, slurry and bone meal.

Question 40

Leaching

Answer 40

Process by which nutrients are washed from the soil into watercourses. Rainwater will dissolve any soluble nutrients, such as nitrate ions and carry them deep into the soil, eventually beyond the reach of plant roots.

Question 41

Eutrophication

Answer 41

Consequence of an increase in nutrient concentrations in watercourses that leads to an algal bloom, leading to light being the limiting factor for the growth of plants and algae at lower depths, leading to saprobiontic bacteria creating an increased demand for oxygen. This leads to aerobic organisms dying and anaerobic organisms populations rising. It leads to a decrease in biodiversity.

Question 42

Greenhouse Gases

Answer 42

Gases such as methane and CO2 which trap more heat energy, raising the Earth