Ecosystems

Question 1

What is a habitat?

Answer 1

The place where an organism lives

Question 2

What is a population?

Answer 2

All the organisms of one species in a habitat

Question 3

What is a community?

Answer 3

All the different species in a habitat

Question 4

What is an ecosystem?

Answer 4

All the organisms living in a particularly area and all the non-living (abiotic) conditions

Question 5

What can you use to estimate a population size?

Answer 5

A quadrat - a square frame enclosing a known area

Question 6

Describe an experiment to estimate a population size

Answer 6

• Place 1m2 quadrat on the ground at a random point within the area you’re investigating
• Count all the organisms within the quadrat
• Multiply the number of organisms by the total area of the habitat
• Repeat in another area and compare the population sizes (get an average)

Question 7

What do you need to think about when using the counting method?

Answer 7

Sample may he not representative of the population - may be different in other places

Sample size affects the accuracy - the bigger the sample, the more accurate your estimate of the total population is likely to be

Question 8

What else can the quadrats be used to investigate?

Answer 8

Distribution of organisms

Question 9

Describe an experienced to show the distribution of organisms

Answer 9

• Mark out a line (transect) in the area you want to study

- Collect data along that line using quadrats placed next to each other

Question 10

What do food chains show?

Answer 10

What’s eaten by what in an ecosystem

Question 11

What does a food chain always start with?

Answer 11

A producer which makes its own food using the energy from the the sun

Question 12

What are producers eaten by?

Answer 12

Primary consumers which are then eaten by secondary consumers which are eaten by tertiary consumers

Question 13

What happens to all the organisms eventually?

Answer 13

• They die and get eaten by decomposers like bacteria.

- Decomposers break down dead material waste

Question 14

What is each stage of a food chain called?

Answer 14

A tropic level

Question 15

What does each bar on a pyramid of numbers show?

Answer 15

The number of organisms at the stage of the food chain

Question 16

What goes at the bottom of a pyramid of numbers?

Answer 16

The organisms that are at the bottom of the food chain

Question 17

What is a typical pyramid of numbers looks like?

Answer 17

Every time you go down the tropic level, the number of organisms decreases

Question 18

What does a pyramid of biomass show?

Answer 18

The mass of the living material at that stage of the food chain (how much all organisms at each level weigh together)

Question 19

What re pyramids of biomass always the same of?

Answer 19

The right shape

Question 20

What are pyramids of energy transfer always the shape of?

Answer 20

Pyramids the right way up like a regular pyramid

Question 21

What do pyramids of energy show?

Answer 21

The energy transferred to each trophic level in a food chain

Question 22

What is energy from the sun a source of for all?

Answer 22

A source of energy for nearly all life on earth

Question 23

What do plants use light energy for?

Answer 23

Photosynthesis from the sun - this energy then works its way through the food chain as animals eat the plants and each other

Question 24

Why is not all the energy that’s available to the organisms in a tropic level passes on to the next level?

Answer 24

90% of energy is lost in varied ways

Question 25

Give some of the examples of how energy is lost

Answer 25

• Not all food is eaten (e.g the roots and bones)
• Some parts of the food are indigestible (e.g. fibre) so pass through and come out as waste
• Energy is used for respiration
• Energy lost to the surroundings as heat

Question 26

How much of the total energy becomes biomass?

Answer 26

10% as it’s stored or used for growth (only energy transferred to the next trophic level)

Question 27

What do food webs show?

Answer 27

How food chains are linked as there are many different species within a environment which means a lot of possible food chains

Question 28

What are all the species in a food web?

Answer 28

Interdependent - if one species is affected, all the others are