Unit 7 Ecology and the Environment flashcards

What is a population?

Individuals of same species in same area at same time.

What is a community?

Multiple populations living and interacting in same area.

What is an ecosystem?

Interaction between the community and the non-living parts of the environment.

What is an abiotic factor?

Non-living factors that affect a community.

List some abiotic factors:

• Light intesity - Light is needed by plants for photosynthesis. More light leads to an increase in rate of photosynthesis and an increase in plant growth rate.

• Temperature - Affects the rate of photosynthesis in plants.

• Moisture levels - Plants and animals require water to survive.

• Soil pH and mineral content - Different species of plants are adapted to different soil pH levels and nutrient concentration levels.

• Wind intensity and direction - Wind speed affects transpiration rate in plants. Transpiration affects the rate of photosynthesis as it ensures water and mineral ions are transported to the leaves.

• Carbon dioxide levels for plants - CO2 is required for photosynthesis in plants. CO2 concentration affects the rate of photosynthesis.

• Oxygen levels for aquatic animals - Some aquatic animals (such as fish) can only survive in water with high oxygen concentrations.

What are biotic factors?

Living factors that affect a community.

List some biotic factors:

• Availability of food - More food means organisms have a higher chance of surviving and reproducing. This means their populations can increase.

• New predators - In balanced ecosystems Predators catch enough prey to survive but not so many that they wipe out the prey population. If a new Predator is introduced to the ecosystem it may become unbalanced.

• New pathogens - If a new pathogen enters an ecosystem, the populations living there will have no immunity or resistance to it and the population may decline or be wiped out.

• Competition - If two species compete for the same resources and one is better adapted to take advantage of these resources, then that species will outcompete the other. This may continue until there are too few members of the lesser adapted species to breed successfully.

Why might plants compete for resources?

• Light - Plants require light for photosynthesis in order to produce glucose, which provides them with energy for growth.

• Space - Plants require space above soil (so leaves can absorb maximum sunlight) and below soil (so roots can absorb water and mineral ions)

• Water (from soil) - Water is essential for photosynthesis and therefore plant growth.

• Mineral ions (from soil) - Plants require various mineral ions such as nitrate ions (used to make proteins) and magnesium ions (used to make chlorophyll).

Why might animals compete for resources?

• Food - Food provides animals with the energy they require for growth and reproduction.

• Mates - Animals require mates in order to reproduce and pass on their genes.

• Territory - Some animals compete for territory. This is an area of habitat that provides an individual with resources such as water, food, shelter and mates.

What are the 3 different types of adaptations?

1) Structural - A physical part or feature of an organisms, that enable it to survive.

2) Behavioural - The actions an organism does to survive.

3) Functional adaptations - The adaptations of an organisms which enable it to carry out major life processes.

What is an adaptation?

Adaptations - are specific features of an organism which enable them to survive in the conditions of their habitat.

What are producers?

Organisms which can make their own organic matter from carbon dioxide and water using sunlight for energy.

What is a primary consumer?

Organisms which eat herbivores.

What is a secondary consumer?

Organisms which eat primary consumers.

What is a tertiary consumer?

Organisms which eat secondary consumers.

Why are pyramids of number not a very good representation of the energy available at each trophic level of the food chain?

Pyramids of number don't show the size/biomass of an organism, and a single large organism can possess far more energy than multiple small ones, but the pyramid only depicts them as 1 unit.

Why are pyramids of biomass more effective than other representations?

A pyramid of biomass shows an estimate of the total mass of organisms in each level of the food chain. This removes the problem of different organisms being different sizes.

What is biomass?

Biomass = the mass of living material in a organism.

What is the equation for biomass (for a pyramid of biomass)?

Biomass = number of organisms x average mass (at each stage of a food chain)

However some energy is lost between the different trophic levels, why?

• Heat from respiration - used in respiration to give energy for movement/growth

• Lost in urine/faeces - not all ingested material is absorbed, some is egested as faeces

• Used for movement

How do you work out the energy efficiency at each trophic level?

Efficiency = useful energy output / total energy output x 100

What is decay?

Decay - the breakdown of dead or waste material by microorganisms like, bacteria and fungi.

Why is decay important?

It allows the energy and materials like carbon to be recycled.

What are conditions that promote decay?

• Moist - essential for microorganisms to survive, because the moisture helps dissolve molecules, to absorb for nutrients.

• Warm - microorganisms are more active in warmer temperatures, as have more kinetic energy

• Abundance of oxygen - microorganisms in food need oxygen to respire

What conditions prevent decay?

• Cold - slow the growth of microorganisms

• Absence of oxygen

• Dry

What are detrivores?

Organisms that feed on dead/decaying material

Write a brief description on RP 10: Decay.

It investigates the effect of temperature on the rate of decay of fresh milk by measuring pH change.

You will use an alkaline solution of milk. When lipase is added to the milk the fat in the milk is broken down into fatty acids. This makes the pH lower.

Cresol red is an indicator that is purple in alkaline solutions of about pH9. When the pH drops below pH 8.3 Cresol red becomes yellow.

Describe the method for RP 10: Decay.

1. Label 2 test tubes: lipase, milk

2. In the lipase test tube put1\operatorname{cm}^3 of lipase solution

3. In milk tube add 1\operatorname{cm}^3 of milk. Add 1.5\operatorname{cm}^3 of sodium carbonate solution to the milk tube. Add 5 drops of Cresol red solution. (The solution should be purple/pink)

4. Put separately in a water bath for 1 minute

5. Mix the 2 test tubes and start the stopwatch

6. Record the time taken (s) for the colour to change from purple to yellow

7. Fill in results into spreadsheet

8. Repeat steps 2-7 at different temperatures

Why did the rate of decay increase as the temperature increased?

• As temperature increases so does the kinetic energy

• This means there are more collisions

• This means the enzyme's active site is combining with the substrate to form an enzyme substrate complex.

• In this practical the substrate is milk and the product is fatty acids and glycerol.

• This results in more product and a faster rate.

• The rate slows as the high temperature causes the enzyme to start to denature. This is where the active site begins to lose its 3D shape.

What were some limitations of this practical? and why was it a limitation? and how could this be improved?

• Difficult to judge colour change - colour is objective - use a pH probe.

• Removing test tube from water bath to check colour - temperature change affects colour - use a pH probe.

• Decay is caused by organisms such as bacteria not just the enzymes they produce - using just enzymes it is likely the rate is artificially high - use bacteria that has sit over a few days.

• What were some hazards of this practical? And how could they be controlled?

• Water bath - Steam burns when lifting lid - limit temp. to 60/70°C / water level significantly lower below level of test tubes.

• Cresol red - damaging to the environment - test tube with remnants to go into waste ice cream tube.

Harmful if ingested - use dilute conc. / Wash off skin / safety glasses.

• Lipase - irritant - safety glasses / conc. relatively dilute

• Sodium carbonate solution - irritant - Very dilute solution / safety glasses