COMMUNICATING10.Construction of Biosphere 2 was completed in- It was designed so a crew of eight people
could live for two years completely isolated
(except for communication contact) from the rest
of the world. They were to care for and survive
off resources (including plants and animals)
placed inside the building. During this process,
they were to learn how this could be done on a
larger scale, perhaps even on another planet.
Unfortunately, not everything went as planned.
Oxygen levels inside the building dropped so
low that more had to be pumped in, breaking
the rule of isolation. Crops did not grow as
well as expected and nearly all the animals
placed in the building died (only cockroaches
and ants reproduced abundantly). What are
some of the things that might have happened to
produce these results? If you have any ideas,
suggest how the problems you described might
have been corrected.
11.Some ecologists like to emphasize ecosystem
processes more than ecosystem structure.
Rather than labelling organisms as producers,
consumers, and decomposers, they note that
most organisms can play all these roles. These
ecologists identify three basic ecosystem
processes: production (the incorporation of
energy and materials into bodies), consumption
(the use of organic molecules for growth and
reproduction), and decomposition (the
breaking down of large organic molecules with
the release of nutrients they contain into the
atmosphere, soil, or water). With this in mind,
explain why plants could be considered
consumers as well as producers, and why
animals might be called producers. Various
kinds of organisms that are commonly referred
to as decomposers can each be thought of as
taking a different role in the breakdown
process. Look up definitions for “scavenger”
and “detrivore,” and give examples of each
type of decomposer. In what way can these
organisms also be thought of as consumers —
and even producers?
12.Design a flowchart to illustrate what happens
to solar energy as it enters the biosphere, is
converted by producers to chemical energy,
and moves up to tertiary consumers. Be sure to
show all the things that happen to the various
amounts of energy along the way.
13.There are two schools of thought about the
formation of ecological communities. While
some scientists think that biotic factors are
most important in determining what species
make up a community, others hold the view
that abiotic factors are more significant.
Research the concepts to discover more about
this debate, and come to your own conclusions462 MHR • Unit 5 Population Dynamics
8.Calculate the Sun’s overall efficiency in
sustaining life using the following information.
(a)98 percent of the Sun’s energy is unused
(b)of the two percent used by plants, only
0.6 percent ends up in glucose (assume
glucose is the only useable energy form
created by photosynthesis)
(c)half of the glucose is used by plants for
their own life processes
(d)60 percent of the glucose reaching your
cells is used to make ATP(e)your usage of energy is 55 percent efficient
Why do you think these processes are not
100 percent efficient? What would happen if
the efficiencies of these processes doubled?
tripled?
9.Assume that a human lives entirely on the
meat of a single species of bird, and that the
bird only eats herbivorous insects. Estimate
how much plant material this person would
need to consume directly in order to gain 1 kg
of weight.4.Give three reasons why solar energy is not
completely converted to chemical energy by
primary producers.
5.Which are more common in nature, food
chains or food webs? Why?6.How do the biogeochemical cycles of elements
that can exist as gases in the atmosphere differ
from the cycles of those elements that do not
have a gaseous form?
7.Describe the roles of plants in an ecosystem
with respect to:
(a)energy flow (b)nutrient cyclingINQUIRY