B2 - Understanding Our Environment

Question 1

Which groups are organisms classified into?

Answer 1

• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

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Question 2

What are the two different forms of classifying species?

Answer 2

1. **Artificial system **- based on one or two characteristics to make identification easier
2. Natural system - based on evolutionary relationships and genetic similarities between organisms

Question 3

How could the classification of an organism change overtime?

Answer 3

DNA Sequencing allows scientists to see the genetic diffrence between organisms, therefore some organisms could be re-classified into different groups

Question 4

What does the term **Species **mean?

Answer 4

A groups of organisms that can interbreed to produce fertile offspring

Question 5

How are organisms named?

Answer 5

Organisms are named by the binomial system, there are two parts to the name

1. Genus - starts with capital
2. Species - starts with lower case

Question 6

What are the problems with classifying?

Answer 6

• There are different organisms that are in different stages of evolution & new organisms are being discovered therefore its hard to put them into a distinct group
• Bacteria - they don’t interbreed and reproduce asexually, therefore they can’t be classed as different species.
• Hybrids- produced by two members of different species interbreeding, the offspring is infertile so it can’t be classes as species

Question 7

What is the pyramid of biomass?

Answer 7

It shows the dry mass of a living material at each stage of a food chain

Question 8

Why might a pyramid of biomass look different compared to a pyramid of numbers?

Answer 8

• If the producers are very large
• If small parasites live on a large animal

Question 9

Why might a POB (pyramid of biomass) be more difficult to construct even though it shows the different trophic levels better?

Answer 9

• some organisms feed on organisms from different trophic levels
• Measuring dry mass is difficult as it involves removing alll of the water from an organism. therefore killing it

Question 10

What can the energy along the food chain be wasted as?

Answer 10

• heat from respiration
• egestion
• excretion

Question 11

Why might the material at each stage of a trophic level, not be wasted?

Answer 11

The lost energy is used by decomposers that can start another food chain

Question 12

Why can’t there be more than roughly five trophic levels in a pyramid of biomass?

Answer 12

So much energy is lost at each stage that it isn’t sustainable for the organism at the top of the food chain

Question 13

How do you work out the efficiency of energy transfer?

Answer 13

efficiency = _energy used for growth _

                         energy input                  X 100

Question 14

How is CO₂ released into air?

Answer 14

• plants & animals **respiring **
• soil bacteria & fungi acting as decomposers
• burning of fossil fuels (combustion)

Question 15

How can CO₂ be absorbed from the air by the ocean and how is it released again?

Answer 15

• There are marine organisms that make shells made out of carbonate, this becomes limestone rocks
• the carbon in limestone can return in the air as CO₂ during volcanic eruptions or weathering

Question 16

carbon cycle diagram

Question 17

What do plants use nitrogen for?

Question 18

What happens to the nitrogen compounds in dead organisms?

Answer 18

They are broken down by decomposers & returned to the soil

Question 19

What are the microorganisms responsible for recycling nitrogen?

Answer 19

1. Soil bacteria/fungi - known as decomposers & they convert proteins into ammonia
2. **Nitrifying bacteria - **converting ammonia to nitrates
3. **Denitrifying bacteria - **converts nitrates to nitrogen gas
4. Nitrogen-fixing bacteria - live in root nodules of legume plants and they fix nitrogen gas into nitrogen compounds through lightening. They have a mutualistic relationship with the plant, the bacterua gets food (sugar) from the plant and the plant gets the nitrogen compounds it need in able to make proteins and grow

Question 20

Nitogen cycle

Question 21

What do decomposers need in able to break down dead materia in soil?

Question 22

Where will decay be slowest at & why?

Answer 22

• Decay will be slowest at waterlogged soil as there is less oxygen
• Also acidic conditions will slow down decay

Question 23

What does the term **ecological niche **mean?

Answer 23

The role of an organism within an ecosystem

Question 24

What are the two different types of competition?

Answer 24

1. **INTERSPECIFIC - **between organism of different species
2. **INTRASPECIFIC **- between organisms of the same species

Question 25

What does a predator and prey relationship show?

Answer 25

It shows the cylical changes (up & down) in their numbers

Question 26

Why are most predator and prey relationships cylical in their numbers?

Answer 26

* When there are a lot of prey, more preditors are able to survive therefore the numbers increase * This means that the number of prey increased will drop, this means that the number of preditors will also drop * The more predators starved meaning a drop in numbers

Question 27

Why does it take a while in order for the predator numbers to peak when the prey peaks?

Answer 27

This is because it takes a while for increased supply of food to allow more predators to survive & reproduce

Question 28

What is a **parasite**?

Answer 28

A parasite is an organism that live on or in a host and feeds from it, mostly causing the host to suffer from the relationship e.g. mosquitos/fleas

Question 29

What is meant by the term **mutualism**? Give examples

Answer 29

Where both organisms can benefit due to their dependant relationship 1. Insects transfer pollen from visiting flowes & rewarded by sugary nectar 2. Cleaner fish cleans parasite out of big fishes teeth & in return they get food

Question 30

What are pea plants?

Answer 30

Pea plants are legumes with structures their roots known as **nodules**, in these nodules live **nitrogen fixing bacteria**

Question 31

Explain the mutualistic relationship between a pea plant and the nitrogen fixing bacteria

Answer 31

1. The bacteria turns nitrogen into nitrogen-containing chemicals & give some to the pea 2. The pea plant gives the beacteria some sugars produced by photosynthesis

Question 32

How does a parasite become adapted?

Answer 32

It does not kill the host quickly or else it would have to find another host

Question 33

What is the feature in animals in cold conditions that reduces heat loss?

Answer 33

Through **anatomical adaptations**

Question 34

What are the anatomical adaptations in colder climates?

Answer 34

Excellent Insulation: * Thick fur (e.g arctic foxes) - traps the air for insulation * Seals - Thin fur but thick layer of fat under the skin * The animals are usually large with small ears, helps to decrease heat loss because it decreases surface area to volume ratio

Question 36

What are behavrial adaptations that some animals have in colder climates?

Answer 36

* They migrate to warmer distances, even travelling long distances * Others slow down their body processes or hibernate

Question 37

How have Penguins adapted to reducing heat loss

Answer 37

They have the **counter current heat exchange mechanism** 1. Blood vessels going to and from the feet carry blood that flows in opposite directions 2. The vessels pass close to each other, allowing heat to transfer between them 3. Warm blood entering the flippers warms up cold blood leaving, stopping body cooling down

Question 38

What are biochemical adaptations that organisms have in colder climates?

Answer 38

Anti-freeze Proteins

Question 39

What are anatomical adaptations that help organisms increase heat loss in hot climates?

Answer 39

* Camels - little hair on the underside of their bodies * Animals are usually smaller & have large ears, meaning they have a larger sufrace area to volume ratio

Question 40

What are behavioural adaptations that organisms have in hotter climate?

Answer 40

* panting/licking fur * Seek shade at hotter hours

Question 41

What are the behavioural, anatomical and physiological adaptations that organisms have in dry conditions

Answer 41

* Camels survive with little water as the can produce concentrated urine * Cacti reduce water loss as their leaves are reduced to spine. Also, they have deep roots & can store water in the stem

Question 42

What are organisms that can withstand extremely hot conditions and suggest a reason why?

Answer 42

* **Extremophiles** * Some bacteria have enzymes that dont denature at temperature as high as 100°C

Question 43

What are **specialists**? what could be the problems with these types of organisms?

Answer 43

* They organisms that are highly adapted to a specific habitat (e.g polar bears) * They would struggle to live in changing habitats and would be out competed

Question 44

What are **Generalists**? What could be the problems?

Answer 44

* Organisms that are adapted to live in a range of different habitats * They could be out competed by the specialists in stable habitats

Question 45

What are different types of pollution caused by?

Answer 45

* **Carbon dioxide** - increases burning of fossil fuels, which increases greenhouse gases & **global warming** * **CFCs -**from aerosols which destroys the ozone layer * **Sulfur Dioxide -** burning fossil fuels causes acid rain

Question 46

What is **exponential growth**?

Answer 46

When the human **population** of the world is growing at an ever-increasing rate, when the birth-rate exceed the death rate

Question 47

What is the **Carbon Footprint**?

Answer 47

The amount of pollution caused per person/organisation, it measures the total **greenhouse gas** given off in a certain time

Question 48

How can pollution in air/water be measured?

Answer 48

* Indicator organisms * Direct methods