Climate

Question 1

Discuss the benefits and risks to society of using these two sources of plant chemical
energy as fuels. [12]

Answer 1

Benefits of Using Biofuels
1. Renewability: Biofuels are produced from crop plants which can be grown repeatedly
and relatively quickly, leading to a sustainable energy source. Unlike fossil fuels,
which take millions of years to form, biofuels
2. Carbon Neutrality: Biofuels are often considered carbon-neutral because the carbon
dioxide (CO2) they release when burned is roughly equal to the CO2 absorbed by the
plants during their growth. This can help reduce net* greenhouse gas emissions,
which contribute to global warming.
3. Energy Security: Producing biofuels domestically can reduce dependence on
imported fossil fuels, enhancing a country’s energy security and economic stability.
4. Waste Reduction: Some biofuels can be made from agricultural waste or non-food
crops, reducing waste and providing a use for by products that would otherwise be
discarded.
Risks of Using Biofuels
4. Food vs. Fuel Debate: Growing crops for biofuels can compete with food production,
potentially driving up food prices and leading to food shortages, especially in
developing countries.
5. Deforestation: To grow biofuel crops, large areas of forest might be cleared, leading
to loss of biodiversity, disruption of ecosystems, and increased CO2 emissions due to
the destruction of carbon-sequestering forests.
6. Limited Efficiency: Biofuels generally have a lower energy density compared to
fossil fuels like coal, meaning more biofuel is required to produce the same amount
of energy, which can be less efficient.
Benefits of Using Coal (Fossil Fuels)
7. High Energy Density: Coal has a high energy density, meaning it provides a large
amount of energy per unit of weight. This makes it a very efficient fuel for generating
electricity and powering industries.
8. Established Infrastructure: The infrastructure for mining, transporting, and burning
coal is well-established, making it a reliable and accessible energy source in many
parts of the world.
9. Economic Benefits: In many regions, coal mining is a major industry, providing jobs
and contributing to local and national economies.
Risks of Using Coal (Fossil Fuels)
10. Non-Renewability: Coal is a finite resource formed over millions of years. Once
depleted, it cannot be replaced, making it an unsustainable long-term energy source.
11. Climate change: Burning coal releases significant amounts of CO2, a major
greenhouse gas contributing to climate change.
12. The continued use of coal threatens to exacerbate climate change and its associated
impacts, such as rising sea levels, extreme weather events, and loss of biodiversity.
13. Health Risks: Coal combustion produces other pollutants like sulfur dioxide (SO2)
and nitrogen oxides (NOx), which contribute to air pollution and acid rain.
14. Coal mining is associated with serious health risks, including respiratory diseases like
black lung, as well as environmental health hazards such as air and water pollution.
Note:
Both biofuels and coal have their benefits and risks to society. Biofuels offer a more
sustainable and potentially environmentally friendly alternative to coal, but they come with challenges related to land use, food security, and efficiency. Coal, while energy-dense and
economically significant, poses substantial environmental and health risks, particularly in
terms of its contribution to climate change. Balancing these factors is crucial for making
informed decisions about energy use and transitioning to more sustainable energy systems.

Question 2

Outline how human activities contribute to climate change. [4]

Answer 2

1. Human activities contribute to increased production of CO2 – e.g. of activities include:
   human induced burning of fossil fuels releases CO2;
   increase in decomposing materials, e.g in landfills/sewage increase CO2 release,
   industrial processes, such as in cement works, release CO2;
   burning land and vegetation to clear land for agriculture;
2. CO2 is a greenhouse gas which contribute to the greenhouse effect;
3. Infrared radiation / heat emitted from Earth’s surface is absorbed and re-emitted by
   greenhouse gases,
4. trapping the infrared radiation / heat in the atmosphere resulting in global warming;

Question 3

define weather

Answer 3

the combination of day-to-day / short-term variations in
temperature, humidity, precipitation, wind, cloudiness and other
atmospheric conditions occurring at a specific place and time.

Question 4

define climate

Answer 4

the long-term (years, decades, or even centuries) AVERAGE weather
patterns and may be measured at many different geographic scales – for
example local, regional, or global. More rigorously, it refers to the
statistical description in terms of the mean and variability of relevant
quantities over a period of time ranging from months to thousands or
millions of years.
(relevant quantities include tempt, precipitation and wind)

Question 5

define climate change

Answer 5

a large-scale, long-term shift / change in average weather patterns
or average temperatures. That is, it refers to a statistically significant
variation in either the mean state of the climate or in its variability,
persisting for an extended period, typically decades or longer. Climate
change may result from: natural factors or processes such as changes in the sun’s radiant
energy (also known as solar irradiance), Earth’s orbital cycle and and
volcanic eruptions, or
* persistent anthropogenic (human-caused) changes in the
composition of the atmosphere as a result of emission of greenhouse
gases or changes in land use.

Question 6

define global warming

Answer 6

the overall warming of the planet, based on the long-term
increase in Earth’s average surface temperature.

Question 7

define biomes

Answer 7

Global-scale biogeographic regions characterised by their distinctive
climate, soil conditions and dominant species (includes plants and
animals).

Question 8

define biodiversity

Answer 8

The number, variety, and variability of living organisms, including
terrestrial, marine, and other aquatic ecosystems and the ecological
complexes of which they are part; this includes diversity within species
(genetic diversity), between species (species diversity), and of
ecosystems (ecosystem diversity).

Question 9

define endemic species

Answer 9

Species that are unique to a particular place, not found elsewhere on
Earth. Found especially in mountains or regions that are geographically
isolated such as islands.

Question 10

define ecosystem

Answer 10

A biological community and all of the abiotic factors influencing that
community.

Question 11

define food chain

Answer 11

Sequence of organisms, each of which serves as a source of energy
for the next.

Question 12

define food web

Answer 12

Complex network of many interconnected food chains and feeding
relationships.

Question 13

define habitat

Answer 13

Place or type of place where an organism or population of organisms
lives.

Question 14

define ecological niche

Answer 14

Total way of life, or role of a species in an ecosystem. It includes all
environmental factors (physical, chemical and biological conditions) that a
species needs in order to grow, survive and reproduce in an ecosystem.

Question 15

define anthropogenic climate change

Answer 15

refers to the increased emission of greenhouse gases caused by
human activities. Important greenhouse gases include carbon
dioxide (CO2), methane (CH4) and nitrous oxide (N2O).

Question 16

define burning of fossil fuels

Answer 16

fossil fuels are hydrocarbons such as coal, oil and natural gas. They
were formed from the remains of living
organisms by exposure to heat and pressure in the Earth’s crust over
millions of years ago. Coal was formed from dead plant materials while
crude oil and gas were formed from dead marine organisms.

Question 17

define deforestation

Answer 17

Deforestation is the permanent clearing of forests in order to make
the land available for other uses such as agricultural activities.

Question 18

define carbon sink

Answer 18

Carbon sink is any system that absorbs more carbon than it releases
into the atmosphere through the physical and biological mechanism of
the carbon cycle

Question 19

define carbon source

Answer 19

Carbon source is any system that releases more carbon than it
stores, e.g. when human mine coal and burn it, CO2 is released into the
atmosphere.

Question 20

define carbon footprint

Answer 20

the total set of greenhouse gas (GHG) emissions caused
by an individual (lifestyle) or organisation (operation), or by a single
event, service, or product (life-cycle). The emissions are calculated
over a set period, generally a year (or the lifetime of an event or
product), that can then be used as a baseline against which reduction
efforts can be measured.

Question 21

define renewable resources

Answer 21

natural resources that can be replenished or regenerated
over a relatively short period of time, either through natural processes
or human intervention. As long as they are managed sustainably, they
will not run out.

Question 22

define non-renewable resources

Answer 22

Natural resources that are available in limited quantities
Resources
and cannot be replenished within a human lifespan once they are
used up. These resources take millions of years to form.

Question 23

define sustainability

Answer 23

The ability to use resources without using them up faster than they are renewed

Question 24

define dengue

Answer 24

A viral infection transmitted by the bite of an infected
female Aedes mosquito.

Question 25

define disease

Answer 25

a disorder or illness that disrupts the normal functioning of the body or mind, leading to poor health. Each disease is associated with a set of signs and symptoms.

Question 26

define epidemic

Answer 26

An increase, often sudden, in the number of cases of a disease above what is normally expected in that population in that area. Outbreak carries the same definition of epidemic, but is often used for a more limited geographic area.

Question 27

define vector-borne disease (VBD)

Answer 27

A disease that is transmitted to humans (also plants and animals) by a living organism.

Question 28

define viremia

Answer 28

A medical condition where there is presence of virus in the blood.

Question 29

define virulence

Answer 29

The relative capacity / degree of a pathogen to overcome body defenses.

Question 30

with ref to data, explain the isolating mechanisms that prevent gene flow between populations

Answer 30

1. ref to all mechanisms are pre-zygotic reproductive isolating mechanisms 2. both species have diff types of pollinators 3. both species are found at diff altitude 4. petal colour 5. flower length 6. 2 species cannot exchange pollen 7. geographical isolation did occur 8. both species are reproductively isolated 9. ref to physiological isolation + elaboration: diff altitude leading to habitat isolation (pollinators' behaviour based on the flower's characteristics)

Question 31

suggest with reasons what prediction can be made about the chromosome numbers of these 2 plant populations

Answer 31

1. the 2 species have the same number of chromosomes 2. hence meiosis can occur in F1 3. chromosomes are similar enough to pair up during prophase I of meiosis note that the number of chromosomes is not the same as polity level; chromosomes pair up during prophase I of meiosis and not metaphase (they line up)

Question 32

the f1 hybrids produce 50% fewer seeds than either of the 2 parent species.

Answer 32

1. F1 have fewer F2 offspring / reduced reproductive fitness 2. hence are outcompeted by parent species 3. parent species are better adapted (F1 hybrid selective disadvantage, selected against) 4. ref to 'disruptive' selection 5. hybrid breakdown