SNC1D Practice Exam Short Answer Solutions
Part C:
1. What abiotic factors may affect the growth of a maple tree in an Ontario Forest
(3 marks)
Light, temperature, minerals, air, water, salinity(salt content), and acidity are all abiotic
factors. Need to select 3 and explain how the maple tree’s growth would be affected. Ex.
If the tree did not receive enough light then its growth would be stunted.
2. Describe an example of overexploitation. (2 marks)
Overexploitation could include clear-cut forestry. We are using too much
(overexploiting) of our resources (forest) and not leaving any behind to support wildlife
and plant life. If we selectively cut forests that would enable life to be sustained and for
trees to continued to be harvested in the future.
3.What would happen to an ecosystem that had all of its decomposers removed?
(2 marks)
No nutrients would be returned to the soil from the decay of plant and animal life. All
dead animals and plants would remain on the forest floor and eventually producers would
run out of nutrients for growth and would eventually die themselves.
4. A block of copper has a volume of 21.2 cm3. If the density of copper is 8.9
g/cm3, find the mass of the copper. SHOW ALL YOUR WORK! (2 marks)
!
𝐷 = !
𝑚 = (𝐷)(𝑣)
𝑚 = (21.2𝑐𝑚! )(
8.9𝑔
)
𝑐𝑚!
𝑚 = 189𝑔
5. Draw a Bohr-Rutherford model for an atom of 3517Cl and 3517Cl-. Be sure to
indicate the number of protons and neutrons in the nucleus as well as the electron
arrangement on orbits. (3 marks)
35
17
Cl
35
17
Cl-
6. Give an example of an everyday element or compound and describe how its
properties determine how it is used. (3 marks)
Copper – used in plumbing pipes and electrical wiring. It is malleable and ductile which
makes it suitable for both those purposes. It is also not harmful if ingested.
7. A negatively charged rod is brought near several neutral rice puffs. The rice
puffs cling to the rod, but then, a short time later, they fly off in all directions.
Explain why this happens. (3 marks)
Neutrally charged objects are attracted to any charged object. The negative rod attracts
the rice puffs, when they touch some of the electrons are passed into the rice puffs
making them negatively charged. Once the puffs are negatively charged, they have the
same charge as the rod, therefore like charges repel each other and the puffs fly off in all
directions.
8. A hair dryer uses 360,000J of energy in 5.0 minutes. What is its power in
watts? SHOW ALL YOUR WORK! (3 marks)
𝐸
𝑃 = 𝑡 = 5 min 𝑥 60 𝑠𝑒𝑐/ min = 300 𝑠𝑒𝑐𝑜𝑛𝑑𝑠
𝑡
𝑃 = 360,000𝐽
300𝑠
𝑃 = 1200𝑊
9. Draw a circuit that keeps two lights on all the time and can switch two other
light bulbs on an off independently from each other. (3 marks)
10. Describe the stages of our Sun’s life cycle. (3 marks)
1. Started as part of a nebula that condensed. When the pressure and gravity were strong
enough nuclear fusion started which is the birth of our sun. 2. It then entered its main
sequence in which it is fusing hydrogen atoms together to form helium that releases
energy in the form of heat and light. This lasts for about 10 billion years. 3. Once the
hydrogen fuel has run out, the sun will begin to try and fuse helium atoms. Fusion of
helium will cause the sun to expand in size to form a red giant star. 4. Once all the fuel
has run out the sun stops emitting light (no longer a star) and the outer layers of the sun
will be shed leaving a dense cooling object called a white dwarf.
11. Compare the four inner planets with the four outer planets in terms of
composition, size, shape, and position in the solar system. (3 marks)
Inner or Terrestrial Planets – Rocky, dense, small, close to the sun
Outer or Jovian Planets – Mostly gaseous, not very dense, beyond the asteroid
belt(farther from the sun than all the terrestrial planets), very large in comparison to the
terrestrial planets
Part D:
1. Discuss one of the following in terms of its effects on ecosystems:
•
Invasive species – Your answer should include mention of at least
3 of the following: few to no predators, reduce food supply for native species,
compete for nesting and mating sites, can cause a decline in native animal/plant
populations, can cause massive economic and environmental impacts
•
Use of long-lasting pesticides, such as DDT – pesticides can
include herbicides (for plants), Insecticides (for insects), Rodenticides (for small
rodents), and Fungicides (for fungi). Depending on the pesticides used, they can
stay and remain active in the environment for differing lengths of time. DDT is a
long lasting pesticide that lasts in the environment for many years. DDT was toxic
to a wide range of insect species. So its affects within an ecosystem are
widespread due to this long lasting activity and broad range of affected species.
DDT is fat soluble, which means it is capable of dissolving into the fatty tissue of
insects and bioaccumulates. As a result it is highly persistent in food chains and
causes the die-off of many bird species. It also is bioamplified as it moves
through food chains and webs.
•
Deforestation – Forests are integral components to many of Earth’s
regulatory processes. Forests take in carbon dioxide from the atmosphere which
makes them part of the Carbon Cycle. Forests are known as carbon sinks as a
result since much of the carbon they absorb stays within their systems as they
grow and produce sugars through photosynthesis.
Deforestation can increase the concentration of carbon dioxide within the
atmosphere, which would have the effect to help raise global temperatures which
in turn would have massive impacts on ecosystems worldwide. Deforestation also
impacts local animal and plant species. Animals would lose habitat and food
sources, and as a result would likely move out of that area or not survive.
Shade tolerant species of plants are those that thrive in the shade provided by
larger trees. If forests were cut down, these species would lose that shade and may
not thrive in a light right environment. Deforestation would also alter soil
chemistry, and drainage patterns which might degrade the soil and make it poor
for growth in the future.
2. Both hydrogen and helium can be used in balloons. Compare their suitability
for this purpose by comparing their physical and chemical properties in detail.
Hydrogen – gas at room temperature, less dense than air (would float), very chemically
reactive (wants to share its 1 valence electron), flammable
Helium – gas at room temperature, less dense than air (would float), chemically inert (its
valence orbit is full, so it does not need to gain or lose any electrons), not flammable
Both would be suitable to used in balloons as both are less dense than air and would float.
However, due to hydrogen’s reactivity and flammability, Helium is more suitable.
Helium is NOT flammable or reactive so it would remain safe even when near heat or
under slight pressure within a balloon.
3. Describe what someone would have to do to live “off the grid” (ie. Not
connected to the major electrical distribution system.
Develop a method for producing and storing some electrical energy. They could use solar
panels, wind turbines, a geothermal generator and batteries. Or if they live near a stream
they could have a small scale hydroelectric system. Any energy produced would need to
meet the needs of their home.
A well designed and insulated home using a modern LEED certified method will retain
any heat energy very well during the winter months which would reduce the amount of
energy for heating needed. Wood Stoves are good at heating homes so any electrical
energy generated by the above methods could be used only for cooking, washing, and
entertainment.
Cooling the home could be done using lots of windows and shade during the summer
months, rather than air conditioning.