organisms and their environment (topic 19)

Question 1

what is the principal source of
energy input to biological systems

Answer 1

the sun

Question 2

describe the flow of energy

Answer 2

starts with the sun, light energy converted by green plants into chemical energy in form of carbohydrates plants eaten by animals/herbivores and chemcial energy from plant transferred to animal if animal eaten by second animal/carnivore, energy is transferred again as energy flows to each orgnaism some is lost to surrounding in form of heat energy

Question 3

food chain

Answer 3

A method of representing how energy moves from producers to other organisms. A food chain always starts with a producer. It then shows the animal that eats the producer, followed by an animal that eats the first animal, and so on

Question 4

trophic level

Answer 4

the position of an organism in a food chain or food web or ecological pyramid

Question 5

food web

Answer 5

a network of interconnected food chains, It shows the multiple pathways along which energy flows through an ecosystem.

Question 6

producer

Answer 6

an organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis

Question 7

consumer

Answer 7

an organism that gets its energy by feeding on other organisms, may be classed as primary, secondary, tertiary and quaternary according to their position in a food chain

Question 8

herbivore

Answer 8

an animal that gets its energy by eating plants

Question 9

carnivore

Answer 9

as an animal that gets its energy by eating other animals

Question 10

decomposer

Answer 10

as an organism that gets its energy from dead or waste organic material

Question 11

what are examples of human activites that effect food webs

Answer 11

overharvesting species used as food, or by introducing a foreign species to a habitat.

Question 12

overharvesting

Answer 12

Harvesting too high a proportion of a population of animals or plants, causing the population size to decrease.

Question 13

problem with introduction of foreign species

Answer 13

introduction of a foreign species, either deliberately or accidentally, can cause the extinction (or near extinction) of native species.

Question 14

pyramid of numbers

Answer 14

A graphical representation of the number of individuals at each feeding level in a food chain.
bottom bar- always producer
bars organised in trophic level

Question 15

biomass

Answer 15

The dry mass of living material in each organism

Question 16

pyramid of biomass

Answer 16

A graphical representation of the energy available within the biomass at each trophic level in a food chain.
decreases as you move up the trophic levels, decrease in biomass is because of the decrease in energy moving up the trophic levels

Question 17

advantages of using a pyramid of
biomass rather than a pyramid of numbers to
represent a food chain

Answer 17

pyramid of biomass is more accurate representation of the flow of energy through a food chain than a pyramid of numbers, A pyramid of numbers does not show how much energy is transferred, or used, by the organisms in the food chain.

Question 18

pyramid of energy

Answer 18

A graphical representation of the energy available within the biomass at each trophic level in a food chain.
each bar gets smaller while you go up the trophic levels

Question 19

how is energy lost to surroudnigns, in a food chain from producer to herbivore

Answer 19

not all of the plant is eaten
energy is used to build inedible tissues such as wood (cellulose) or roots
energy is lost as heat during respiration

Question 20

how is energy lost to surroudnigns, in a food chain from producer to herbivore from herbivore to carnivore

Answer 20

energy is lost as heat
energy is lost as excretory products (for example, urea)
energy is used to build up inedible parts such as bones
energy is used up by the herbivore to carry out biological activities.

Question 21

why is it that food chains normally have less than 5 trophic levels

Answer 21

The further you go along the food chain, the less energy is available.
A large amount of energy is lost at each level of the food chain. As a result, the amount of energy that is transferred up the food chain is less and less at each level

Question 22

advantages of using pyramids of energy instead of biomass

Answer 22

most accurate at representing a food chain because it shows the actual energy transferred from one trophic level to the next. Two organisms may have the same biomass but different amounts of energy.

Question 23

disadvantage of using an energy pyramid

Answer 23

it is difficult to measure the amount of energy that an organism has.

Question 24

Explain why it is more energy efficient for humans to eat crop plants than to eat livestock that have been fed on crop plants

Answer 24

Energy from the Sun is absorbed by plants and used to form stems, leaves and tubers. Approximately 10% of this energy is transferred to livestock animals that eat the plants

Question 25

carbon cycle

Answer 25

describes how carbon moves through the environment. It involves processes by living organisms and processes that do not involve living organisms

Question 26

what are the processes involved in the carbon cycle

Answer 26

photosynthesis, respiration, feeding,
decomposition, formation of fossil fuels and
combustion

Question 27

carbon cycle- photosynthesis

Answer 27

removes carbon from air
plants converts carbon dioxide into carbohydrates

Question 28

carbon cycle- feeding

Answer 28

carbs produced in photosynthesis are used in the synthesis of carbon compounds in the plant, consumed by herbivores, digested and used to make carbon compounds in the herbivores, transferred to carnviores. decomposers eg. bacteria or fungi also feed on dead plants and animals ingesting their carbon compounds

Question 29

carbon cycle-decomposition

Answer 29

fossil fuels fromed from remains from dead orgnaims whcih undergo partial decomposition, carbon in these organisms remain trap and compressed in soil,a cting as a store for carbon

Question 30

what are ways carbon dioxide are returned to enviornment

Answer 30

respiration
combustion.

Question 31

carbon cycle- respiration

Answer 31

Respiration by plants, animals and decomposers releases carbon dioxide into the atmosphere.

Question 32

carbon cycle- combustion

Answer 32

combustion of fossil fuels releases carbon dioxide into the atmosphere. The combustion of trees and other plants also releases carbon dioxide into the atmosphere.

Question 33

what are soem carbon stores

Answer 33

the atmosphere
oceans
land biomass
fossil fuels

Question 34

nitrogen fixation

Answer 34

Nitrogen fixation is the process by which unreactive nitrogen gas is converted into more reactive forms of nitrogen. This can happen in two ways: lightning, nitrogen-fixing bacteria

Question 35

nitrogen fixation- lightning

Answer 35

lightning bolt passes through the atmosphere, the energy of the lightning makes some nitrogen gas molecules combine with oxygen gas to form nitrogen oxides such as nitric oxide and nitrogen dioxide. These oxides dissolve in the rainwater and are washed into the soil to form nitrate ions.

Question 36

nitrogen fixation- nitrogen- fixing bacteria

Answer 36

Nitrogen-fixing bacteria live freely in the soil, and inside the nodules of leguminous plants such as beans and peas. These bacteria convert nitrogen gas in the air between soil particles to ammonia (which dissolves to form ammonium ions).

Question 37

denitrification

Answer 37

Process that converts nitrates from the soil into nitrogen gas. denitrifying bacteria in the soil carry out this process

Question 38

nitrification

Answer 38

Ammonium ions in the soil are converted to nitrate ions involve nitrifying bacteria in the soil

Question 39

how are plants invovled in the nitrogen cycle

Answer 39

Plants absorb nitrate ions through their root hair cells by active transport, used to make amino acids used in synthesis of protein proteins transferred to herbivroes when fedding, which are digested forming amino acids, used to make protein…

Question 40

Nitrogen is returned to the environment from animals and plants in two main ways

Answer 40

deamination in animals
decomposition.

Question 41

deamination

Answer 41

The removal of the nitrogen-containing part of amino acids to form urea.

Question 42

decomposition- nitrogen cycle

Answer 42

Decomposers break down plant and animal proteins, and waste materials, to form ammonium ions. These ions can be nitrified to form nitrate ions. These ions may then be absorbed by plants or denitrified to form nitrogen gas.

Question 43

summarise processes in nitrogen cycle

Answer 43

nitrogen fixation= nitrogen gas to ammonium ions
nitrification=ammonium ions to nitrate ions
(via nitrite ions)
denitrification=nitrate ions to nitrogen gas
decomposition=proteins to ammonium ions

Question 44

population

Answer 44

a group of organisms of one species, living in the same area, at the same time

Question 45

community

Answer 45

all of the populations of different species in an ecosystem

Question 46

ecosystem

Answer 46

a unit containing the community of organisms and their environment, interacting togethe

Question 47

which factors affect rate of growth and number of idnivudals in an ecosystem

Answer 47

food supply-increase= more organisms survive decrease= less organisms survive fight for resources

predation-The act of catching and killing prey for food.,rate of predation of a population is faster than the rate of breeding, more organisms are killed than are born. As a result, the population will decrease

disease-Disease epidemics affect many individuals at once in a population. They can reduce the size of a population very quickly, either by the death of individuals or by reducing the ability of individuals to reproduce.

competition-Animals compete for food, water, shelter, even mates. Plants compete for water, light and minerals.

Question 48

which Four factors determine how the size of a population changes over time:

Answer 48

Number of births: this increases the population size because offspring are added.

Immigration: this increases the size of the population because individuals come into the area from somewhere else.

Number of deaths: this decreases the population size because some individuals are eaten, or die of old age or illness.

Emigration: this decreases the size of the population because individuals leave the area to go somewhere else.

Question 49

what are the four phases in a sigmoid curve in order

Answer 49

lag, log, stationary, death

Question 50

what does a sigmoid curve represent

Answer 50

population growth for a population growing in an environment with limited resources

Question 51

explain lag phase

Answer 51

slow increase in population size, takes time for the population size to increase because there are relatively few individuals capable of reproducing.

Question 52

explain log phase

Answer 52

resources are relatively plentiful, so the individuals reproduce at a high rate resulting in an exponential increase in population size.

Question 53

stationary phase

Answer 53

resources are limited, competition is high
animals compete for food, water, space and mates
plants compete for light, water, space and nutrients in the soil.
no increase in population size as the number of individuals dying is equal to the number being reproduced.

Question 54

death phase

Answer 54

a rapid decrease in the size of the population. It is caused by a change in the environment such as the presence of a new predator, new pathogen, new competing species, drought or if the food supply or nutrients run out.

Question 55

limiting factor

Answer 55

The variable in the environment that controls the rate, growth or abundance of a biological processes. environmental resistance factors

Question 56

carrying capactiy

Answer 56

The maximum population size of a species that can be sustained by its environment.