Living Organism and Environment

Question 1

Methods to collect organisms

Answer 1

pooter (small animals)
pitfall trap (crawling insects)
plankton net plankton
net (flying or aquatic)
tullgren funnel small animals

Question 2

Quadrats- distribution and abundance for organisms in a uniform ecosystem grassland

Answer 2

A quadrat is a square frame whose area is known, e.g.
0.25 m2 or 1 m2. It is placed, at random, several times
within the ecosystem. The number of individuals of each species of plant and stationary or slow-moving animal found within the quadrat is counted.

Question 3

line transects

Answer 3

A line transect is usually a measuring tape or string that has marks at regular intervals, e.g. 10 cm or25 cm. It is placed in a straight line across the ecosystem and the species of plants and stationary orslow-moving animals touching the line, or touching the line at each mark, are recorded.

rocky seashore, how populations of species changes across an ecosystem trnasition of organsims

Question 4

belt transect

Answer 4

A belt transect is a strip of fixed width, e.g. 0.5 m or 1 m, made by placing two parallel line transectsacross an ecosystem. The species found between the lines are recorded.

Question 5

species density

Answer 5

If the quadrat is 1 m2, it is obtained by dividing the total number of individuals of the species by the number of quadrats used.

Question 6

total popultion

Answer 6

It is obtained bymultiplying the species density by the total area of the ecosystem studied

Question 7

species cover, percent of ground covered by a given species

Answer 7

If the quadrat is 1 m2
, it is obtained by dividing the totalpercentage of ground that the species covered by the number of quadrats used.

Question 8

species frequency

Answer 8

percent of quadrats s in which the given species was found.

Question 9

estimate population size

Answer 9

to estimate population sizes of moving animals. A representative sample of animals of a species is collected, the animals are counted and each one ismarked, e.g. with a dot of paint. The animals are released back into the same area and given time to mix with the original population. A second sample is collected, counted and the number of marked organisms counted.

The population size is then estimated:
estimated population size = number of organisms in first sample X number of organisms in second sample
DIVIDED BY
number of marked organisms recaptured

Question 10

Climatic factorS

Answer 10

THWALA

Question 11

AQUATIC FACTORS

Answer 11

SWD

Question 12

NON RENEWABLE RESOUCRES

Answer 12

Non-renewable resources are present in the Earth in finite amounts; they cannot be replaced, and consequently they are running out

Question 13

NON RENEWABLE RESOURCES ARE

Answer 13

Energy resources such as fossil fuels, i.e. petroleum (crude oil), natural gas and coal, and radioactive fuels, e.g. uranium.
* Mineral resources such as iron ore, bauxite (aluminium ore), copper and tin.

Question 14

RENEWABLE RESOURCES

Answer 14

Renewable resources can be replaced by natural processes. However, many plant and animalspecies are being overexploited such that their numbers are decreasing, in some cases to the point of extinction.

• Many marine organisms are being overfished for food, e.g. lobsters, whales, turtles, sea eggs and conch. * Some terrestrial organisms are being overhunted for products such as fur and ivory, e.g. mink, seal and elephants

Question 15

DEFORESTATION

Answer 15

• Vast areas of forest are being cut down to provide land for housing and agriculture, and to providematerials for fuel, building and the manufacture of paper. This deforestation leads to:

1. The loss of a habitat for plants and animals.
2. The destruction of plants and animals living in the forests. Some of these may eventually become extinct.
3. A reduction in photosynthesis resulting in a gradual increase in atmospheric carbon dioxide levels which is contributing to the greenhouse effect (see page 26).
4. Disruption of the water cycle.
5. Soil erosion caused by the absence of leaves to break the force of the rain and roots to bind the soil.

Question 16

SOIL EROSION LEADS TO

Answer 16

• Soil is being eroded due to** cutting down trees and not replanting, and bad agricultural practices such as leaving the soil barren after harvesting,** **using chemical fertilisers instead of organic fertilisers, **overgrazing of animals and ploughing down hillsides instead of contour ploughing. The loss of soil leads to:

A reduction in the number of trees andother plants that can be grown.

A reduction in the quantity of agricultural crops that can be grown.

Question 17

Pollution

Answer 17

the contamination of the natural environment by the release of unpleasant and harmful substances into the environment

Question 18

negative human activity

Answer 18

human activities such as agriculture, industry, mining and disposal of waste have a negative impact on living organisms and the environment.

pollution
destruction of habitats

Question 19

Pollution caused by the improper disposal of garbage

Answer 19

• Toxic chemicals in the garbage can leach out and contaminate the soil, aquatic environments andwater sources.
• Greenhouse gases, e.g. methane and carbon dioxide, can be released into the atmosphere where they contribute to the greenhouse effect (see page 26).
• Hydrogen sulfide gas can be released into the air. This gas is extremely toxic, and even lowconcentrations irritate the eyes and respiratory system.
• Plastics can enter waterways and oceans where they are harmful to aquatic organisms.
• Bacteria from untreated sewage can enter groundwater and cause disease, e.g. cholera.
• Garbage attracts rodents, which can spread disease.
• Garbage creates an eyesore, which impacts negatively on tourism, especiallyeco-tourism

Question 20

Pollution of marine and wetland ecosystems

Answer 20

Because of their rich biodiversity and beauty, these ecosystems are major contributors to theeconomies of many small island developing states of the Caribbean throughtourism, fisheries andcoastal protection.

Many of these ecosystems are being pollutedby untreated sewage, chemical fertilisers, pesticides,industrial waste, hot water, garbage and oil from oil spills. This pollution impacts negatively on both the overall health of the ecosystems and their aesthetic appeal.

They are also being overfished and destroyed for development purposes, e.g. to build harbours or marinas. Damage to coral reefs, mangrove swamps and other marine and wetland ecosystems results in a loss of:

Question 21

Pollution of marine(coral reefs, mangrove samps, estuaries) salty and wetland ecosystems (marshes bos some mangrove swamps) brackish

Answer 21

*** Biodiversity; coral reefs and mangrove swamps being some of the most biodiverse ecosystems on the planet.

• Habitats for many organisms, e.g. reef fish and mangrove oysters.
• Natural resources, e.g. fish, crabs, lobsters, oysters, seaweeds and wood.
• Attractions and recreational sites for tourists.
• Nursery grounds for reef fish which mangrove swamps provide, resulting in a reduction inpopulation sizes of fish on reefs.
• Nesting and breeding grounds for birds, e.g. egret and scarlet ibis.
• Protection for shorelines against wave action and tidal forces, resulting in increased coastal erosion.
• Flood control provided by wetlands.**

Question 22

economic effects of wetland polution

Answer 22

Due to the pollution and destruction of marine and wetland ecosystems and the coastal erosion that often follows, the tourism and fishing industries of Caribbean states are in danger of declining and this will have a negative impact on their economies.

Question 23

greenhouse effect

Answer 23

Carbon dioxide, water vapour, dinitrogen monoxide (N2O) and methane (CH4) are greenhouse gases. They form a layer around the Earth that lets radiation from the sun pass through but Greenhouse gases absorb some radiation and radiate it back toEarth. This also warms the Earth. This radiation causes warming of the Earth which is known as the greenhouse effect.

Question 24

GREENHOUSE GAS EFFECT

Answer 24

An increase in greenhouse gases, especially carbon dioxide, caused by human activities, e.g. burning fossil fuels and deforestation, is
enhancing the greenhouse effect and resulting in the Earth getting warmer. This warming, called global warming, is leading to global climate change.

Question 25

EFFECTS OF CLIMATE CHANGE

Answer 25

Melting of polar ice caps and glaciers.
* A rise in sea levels.
* Flooding of low-lying coastal areas.

• Changes in global weather patterns, e.g. some areas are becoming drier and others wetter than normal, while some areas are becoming colder and others hotter than normal.
• More severe weather events and natural disasters, e.g. colder winters, hotter summers, moreextensive and frequent floods, droughts and wildfires, and more powerful hurricanes andtornadoes.
• Certain diseases to become more widespread, e.g. malaria.
• A rise in sea temperatures which can cause corals to bleach anddie.

Question 26

OCEAN ACIDIFICATION

Answer 26

Some carbon dioxide is absorbed by oceans causing the pH of the water todecrease, known asocean acidification. This is expected to affect the ability of shellfish to produce and maintain their shells andof reef-building corals to produce their skeletons. This will reduce the chances of survival of theseorganisms which will have a negative impact on marine food chains and fishing industries, and leadto the erosion of coral reefs.

Answer 27

Conserve and restore natural resources
* Use alternative energy sources, e.g. solar, wind and geothermal, instead of fossil fuels.
* Replace renewable resources, e.g. practise reforestation.
* Recycle resources, e.g. glass, plastic, metals and paper.
* Re-use materials, e.g. glass bottles.
Reduce soil erosion, e.g. never leave soil barren and prevent overgrazing by animals
Reduce pollution
* Use alternative energy sources that do not cause pollution instead of burning of fossil fuels.
* Use organic fertilisers instead of inorganic chemical fertilisers.

• Develop educational programmes for people of all ages.
• Pass legislation to protect the environment.
• Sign international agreements to control pollution and conserve natural resources.

Question 28

The rate at which a population grows depends on four factors

Answer 28

the birth rate, the death rate, the rate ofmovement of organisms into the population, i.e. immigration, and the rate of movement of organismsout of the population, i.e. emigration

Question 29

SIGMOID GROWTH CURVE

Answer 29

When members of a species first colonise anarea andstart toreproduce, thebirthrateexceedsthedeathrate and the population increases insize until theareacannot support anymoreindividuals.Thisareaissaid to have reached its carrying capacity. A

Question 30

Population sizes can also be considerably reducedby:

Answer 30

• Natural disasters such as hurricanes, storms, floods, droughts, earthquakes, tsunamis and volcaniceruptions.
• Invasive species, i.e. species that colonise ecosystems in which they, themselves, are non-natives.
• Pests.

Question 31

the human population has grown exponentially since the mid-1800s because humans have:

Answer 31

• Developed modern medicine which has reduced the death rate from disease, improved infantsurvival and increased life expectancy.
• • Improved water supplies, sanitation andhousing whichhave reduced the death rate from disease.
• • Improved agricultural techniques whichhave increased food production.
• • Developed a better nutritional understanding, which has improved health and increased life expectancy

Question 32

factors THAT limit further population growth:

Answer 32

Food shortages start to occur.
* * * Overcrowding begins to occur which causes increased competition for space, a mate, food and shelter in animals, and light, water and mineral salts in plants.
* Diseases start to spread more rapidly.
* Predators begin to increase in number.

Question 33

STATIONARY PHASE

Answer 33

WHERE DEATH RATE AND BIRTH RATE R EQUAL