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Biology 1001 – Midterm 2– Answers
Part A - Multiple Choice.
1) A population is correctly defined as having which of the following
characteristics?
I. inhabiting the same general area
II. individuals belonging to the same species
III. possessing a constant and uniform density and dispersion
A) I only
B) III only
C) I and II only ?
D) II and III only
E) I, II, and III
2) The most common kind of dispersion in nature is
A) clumped. ?
B) random.
C) uniform.
D) indeterminate.
E) dispersive.
3) A population of ground squirrels has an annual per capita birth rate of 0.06 and
an annual per capita death rate of 0.02. Estimate the number of individuals added
to (or lost from) a population of 1,000 individuals in one year.
A) 120 individuals added
B) 40 individuals added ?
C) 20 individuals added
D) 400 individuals added
E) 20 individuals lost
4) A population's carrying capacity
A) can be accurately calculated using the logistic growth model.
B) generally remains constant over time.
C) increases as the per capita growth rate (r) decreases.
D) may change as environmental conditions change. ?
E) can never be exceeded.
5) In a population that is growing as described by the logistic growth model,
A) the number of individuals added per unit time is greatest when N is close to zero.
[The key equation is dn/dt = rmax N(K-N/K).]
B) the per capita growth rate (r) increases as N approaches K.
C) population growth is zero when N equals K. ?
D) the population grows exponentially when K is small.
E) the birth rate (b) approaches zero as N approaches K.2
6) What is the fundamental difference between matter and energy?
A) Matter is cycled through ecosystems; energy is not. ?
B) Energy is cycled through ecosystems; matter is not.
C) Energy can be converted into matter; matter cannot be converted into energy.
D) Matter can be converted into energy; energy cannot be converted into matter.
E) Matter is used in ecosystems; energy is not
7) A cow's herbivorous diet indicates that it is a(n)
A) primary consumer. ?
B) secondary consumer.
C) decomposer.
D) autotroph.
E) producer.
8) The main decomposers in an ecosystem are
A) fungi.
B) plants.
C) insects.
D) prokaryotes.
E) both A and D?
9) In general, the total biomass in a terrestrial ecosystem will be greatest for which
trophic level?
A) producers ?
B) herbivores
C) primary consumers
D) tertiary consumers
E) secondary consumers
10) Which of the following is primarily responsible for limiting the number of
trophic levels in most ecosystems?
A) Many primary and higher-order consumers are opportunistic feeders.
B) Most predators require large home ranges.
C) Nutrient cycles involve both abiotic and biotic components of ecosystems.
D) Nutrient cycling rates tend to be limited by decomposition.
E) Each energy transfer is less than 100% efficient. ?
11) Which of the following statements is consistent with the competitive exclusion
principle?
A) Bird species generally do not compete for nesting sites.
B) The density of one competing species will have a positive impact on the population
growth of the other competing species.
C) Two species with the same fundamental niche will exclude other competing species.
D) Even a slight reproductive advantage will eventually lead to the elimination of
inferior species. ?
E) Evolution tends to increase competition between related species.3
12) The sum total of an organism's interaction with the biotic and abiotic resources
of its environment is called its
A) habitat.
B) logistic growth.
C) biotic potential.
D) microclimax.
E) ecological niche. ?
13) All of the following represent ways that animals defend themselves against
predators except
A) incorporating plant toxins into their tissues.
B) cryptic coloration.
C) mobbing.
D) interspecific competition. ?
E) hiding or fleeing.
14) To measure species diversity in a community, you need to know
A) the number of species.
B) the relative abundance of each species.
C) the physical size of each species.
D) both A and B ?
E) A, B, and C
15) Which of the following statements about succession is correct?
A) Secondary succession occurs where no soil exists.
B) Primary succession occurs in areas where soil remains after a disturbance.
C) Secondary succession can occur where a disturbance has left soil intact. ?
D) Some cases of succession involve facilitation, a phenomenon in which local species
inhibit the growth of newcomers.
E) Through successional dynamics, most communities will eventually become more
stable through time.
16) Which of these terms applies to the relationship between a dog and a blood-
sucking tick?
A) predation
B) competition
C) parasitism ?
D) commensalism
E) mutualism4
17) A community's species diversity is
A) increased by frequent massive disturbance.
B) increased by stable conditions with no disturbance.
C) increased by moderate levels of disturbance. ?
D) increased when humans intervene to eliminate disturbance.
E) increased by intensive disturbance by humans.
18) If most of the individuals of a human population are in their prereproductive
years, you would expect the population size to ________ after 20 years.
A) stay the same
B) increase ?
C) decrease
D) decrease and then stabilize
E) decrease and then decrease more sharply
19) When selecting a mate, females should be choosier than males because
A) males have a higher rate of unfavourable genetic mutation
B) females have a higher investment in each mating?
C) females live longer
D) A and C
E) None of the above
20) The operational sex ratio is
A) the same as the numerical sex ratio
B) dependent on age-specific birth rates
C) usually more male-biased than the numerical sex ratio?
D) applicable only to those animals who reproduce by cloning
E) All of the above
21) Which part of a plant absorbs most of the water and minerals taken up from the
soil?
A) taproots
B) root hairs ?
C) the thick parts of the roots near the base of the stem
D) storage roots
E) sections of the root that have secondary xylem
22) Land plants are composed of all the following tissue types except
A) mesodermal.
B) epidermal.
C) meristematic. ?
D) vascular.
E) ground tissue.5
23) Which functional plant cells lack a nucleus?
A) xylem only
B) sieve cells only
C) companion cells only
D) both companion and parenchyma cells
E) both xylem and sieve-tube cells?
24) Pores on the leaf surface that function in gas exchange are called
A) hairs.
B) xylem cells.
C) phloem cells.
D) stomata. ?
E) sclereids.
25) All of the following cell types are correctly matched with their functions except
A) mesophyll-photosynthesis
B) guard cell-regulation of transpiration
C) sieve-tube member-translocation
D) vessel element-water transport
E) companion cell-formation of secondary xylem and phloem?
26) Which of the following is not a function of the plasma membrane proton pump?
A) hydrolyzes ATP
B) produces a proton gradient
C) generates a membrane potential
D) equalizes the charge on each side of a membrane ?
E) stores potential energy on one side of a membrane
27) If ?P = 0.3 MPa and ?S = -0.45 MPa, the resulting ? is
A) +0.75 MPa.
B) -0.75 MPa.
C) -0.15 MPa. ?
D) +0.15 MPa.
E) impossible to calculate with this information.
28) The value for ? in root tissue was found to be -0.15 MPa. If you take the root
tissue and place it in a 0.1 M solution of sucrose (? = -0.23), net water flow would
A) be from the tissue into the sucrose solution. ?
B) be from the sucrose solution into the tissue.
C) be in both directions and the concentrations would remain equal.
D) occur only as ATP was hydrolyzed in the tissue.
E) be impossible to determine from the values given here.6
29) Which of the following would likely not contribute to the surface area available
for water absorption from the soil by a plant root system?
A) root hairs
B) endodermis ?
C) mycorrhizae
D) fungi associated with the roots
E) fibrous arrangement of the roots
30) What is the role of proton pumps in root hair cells?
A) establish ATP gradients
B) acquire minerals from the soil ?
C) pressurize xylem transport
D) eliminate excess electrons
E) A and D only
31) What is the main force by which most of the water within xylem vessels moves
toward the top of a tree?
A) active transport of ions into the stele
B) atmospheric pressure on roots
C) evaporation of water through stoma ?
D) the force of root pressure
E) osmosis in the root
32) Water potential is generally most negative in which of the following parts of a
plant?
A) mesophyll cells of the leaf ?
B) xylem vessels in leaves
C) xylem vessels in roots
D) cells of the root cortex
E) root hairs
33) Phloem transport of sucrose can be described as going from "source to sink."
Which of the following would not normally function as a sink?
A) young leaf
B) growing root
C) storage organ in summer
D) mature leaf ?
E) shoot tip
34) Water flows into the source end of a sieve tube because
A) sucrose has diffused into the sieve tube, making it hypertonic.
B) sucrose has been actively transported into the sieve tube, making it hypertonic. ?
C) water pressure outside the sieve tube forces in water.
D) the companion cell of a sieve tube actively pumps in water.
E) sucrose has been dumped from the sieve tube by active transport.7
35) Which of these involves a symbiotic relationship?
A) root hairs
B) apoplasts
C) Casparian strips
D) mycorrhizae ?
E) symplasts
36) Which of the following describes the fate of most of the water taken up by a
plant?
A) It is used as a solvent.
B) It is used as a hydrogen source in photosynthesis.
C) It is lost during transpiration. ?
D) It makes cell elongation possible.
E) It is used to keep cells turgid.
37) In hydroponic culture, what is the purpose of bubbling air into the solute?
A) to keep dissolved nutrients evenly distributed
B) to provide oxygen to root cells ?
C) to inhibit the growth of aerobic algae
D) to inhibit the growth of anaerobic bacteria
E) both C and D
38) Which two elements make up more than 90% of the dry weight of plants?
A) carbon and nitrogen
B) oxygen and hydrogen
C) nitrogen and oxygen
D) oxygen and carbon ?
E) carbon and potassium
39) Nitrogen fixation is a process that
A) recycles nitrogen compounds from dead and decaying materials.
B) converts ammonia to nitrate.
C) releases nitrate from the rock substrate.
D) converts nitrogen gas into ammonia. ?
E) both A and B
40) Dwarf mistletoe grows on many pine trees in the Rockies. Although the
mistletoe is green, it is probably not sufficiently active in photosynthesis to produce
all the sugar it needs. The mistletoe also produces haustoria. Thus, dwarf mistletoe
growing on pine trees is best classified as
A) an epiphyte.
B) a nitrogen-fixing legume.
C) a carnivorous plant.
D) a symbiotic plant.
E) a parasite. ?8
B. Define the following terms (2 marks each)
a. competition A (-, -) interaction between members of the same species (Intraspecific)
or between members of different species (Interspecific) for resources that are in short
supply (or limited resources)
b. keystone species - a single species that can influence the structure of an entire
community
c. biodiversity - the entire array of biological variety contained in genes, populations,
communities, and ecosystems
d. turnover time = Standing crop biomass (mg/m2
) / Production (mg/m2
/day)
OR -a measure of how long material remains at one level in a food pyramid
e. resource partitioning-differentiation of ecological niches based on that allows two
species to coexist
Label the following diagrams or fill in the blanks(1 mark each)
a. EXPONENTIAL GROWTH
b. LOGISTIC GROWTH
c. CARRYING CAPACITY (K)
2. Complete the following:
Gross primary production – respiration = NET PRIMARY PRODUCTION
Species diversity increases along a gradient from the POLES to the EQUATOR
A Type III survivorship curve has a higher death rate in YOUNGER individuals
************
d. FREQUENT DISTURBANCE WIPES OUT A COMMUNITY
e. COMPETITION REDUCES COMMUNITY DIVERSITY
f. This graph represents the INTERMEDIATE DISTURBANCE Hypothesis
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