The Brazil nut tree, Bertholletia excels (n = 17), is native to tropical rain forests of South America. It is a hardwood tree that can grow to over 50 meters, is a source of high-quality lumber, and is a favorite nesting site for harpy eagles. As the rainy season ends, tough-walled fruits, each containing 8?25 seeds (Brazil nuts), fall to the forest floor. About $50 million worth of nuts are harvested each year. Scientists have discovered that the pale yellow, self-incompatible flowers of Brazil nut trees admit only female orchid bees as pollinators.
Animals that consume Brazil nuts are deriving nutrition mostly from tissue whose nuclei have how many chromosomes?
A) 17
B) 34
C) 51
D) 68
E) There is not enough information to say.
Answer: C
The agouti (Dasyprocta spp.), a cat-sized rodent, is the only animal with teeth strong enough to crack the hard wall of Brazil nut fruits. It typically eats some of the seeds, buries others, and leaves still others behind inside the fruit, which moisture can now enter. The uneaten seeds may subsequently germinate. Consequently, which terms describe the relationship between the Brazil nut tree and the agouti?
1. parasitic
2. commensalistic
3. symbiotic
4. endosymbiotic
5. mutualistic
A) 1 and 3
B) 2 and 4
C) 2 and 5
D) 3 and 5
E) 4 and 5
Answer: D
Entrepreneurs attempted, but failed, to harvest nuts from plantations grown in Southeast Asia. Attempts to grow Brazil nut trees in South American plantations also failed. In both cases, the trees grew vigorously, produced healthy flowers in profusion, but set no fruit. Consequently, what is the likely source of the problem?
A) poor sporophyte viability
B) poor sporophyte fertility
C) failure to produce fertile ovules
D) failure to produce pollen
E) pollination failure
Answer: E
The agouti is most directly involved with the Brazil nut tree's dispersal of A) male gametophytes.
B) female gametophytes.
C) sporophyte embryos.
D) sporophyte megaspores.
E) female gametes.
Answer: C
The harpy eagle, Harpia harpyja, is the largest, most powerful raptor in the Americas. It nests only in trees taller than 25 meters. It is a "sloth specialist," but will also take agouti. Thus, if these eagles capture too many agoutis from a particular locale, they might contribute to their own demise by A) having too many offspring.
B) increasing habitat loss.
C) decreasing atmospheric CO2.
D) increasing the number of sloths.
Answer: B
Brazil nut trees begin producing fruit at the age of 10 years, reach final height at about 120 years, and can live for over 500 years. A landowner can earn more by felling a Brazil nut tree and selling it for lumber than from several seasons' worth of Brazil nut harvests from the same tree. Thus, it makes greater financial sense in the long run to harvest
A) all of the Brazil nut trees and sell them for lumber.
B) all of the nuts, and only then harvest all of the trees.
C) the nuts for many seasons.
D) remove no resources from the forest.
Answer: C
Native peoples traditionally use Brazil nuts to treat stomach ache, inflammation, hypersensitivity, and hepatitis. Consequently, a scientist should be interested in promoting
A) better education for the native peoples so that they will overcome their old ways.
B) clear-cutting forests containing Brazil nut trees to make way for crops with proven medical benefits.
C) an increase in the living standards of the native peoples so that they might be able to purchase modern pharmaceuticals.
D) the evaluation of Brazil nut chemicals for use as potential drugs.
E) that free, FDA-approved medicines be provided to the impoverished natives.
Answer: D
To help ensure a prosperous future for the largest number of people, developed countries should
A) help underdeveloped countries to more effectively exploit and market their natural resources.
B) apply sanctions on developing countries that fail to curtail their rates of growth and development.
C) conserve at home and exploit resources abroad.
D) reuse, recycle, and reduce at home, while encouraging the same abroad.
E) work for the removal of indigenous peoples from endangered habitats, so as to better preserve limited resources in those habitats.
Answer: D
In the long run, harvesting Brazil nut trees for their lumber is most likely to benefit
A) harpy eagles.
B) later generations of humans.
C) agoutis.
D) orchid bees.
E) sloths.
Answer: E
People who attempted to plant Brazil nuts in hopes of establishing plantations of Brazil nut trees played roles most similar to those of
A) agoutis.
B) orchid bees.
C) pollen tubes.
D) harpy eagles.
Answer: A
The same bees that pollinate the flowers of the Brazil nut trees pollinate orchids, which are epiphytes (in other words, plants that grow on other plants); however, orchids cannot grow on Brazil nut trees. These observations explain
A) the coevolution of Brazil nut trees and orchids.
B) why Brazil nut trees do not set fruit in plantations.
C) why male orchid bees do not pollinate Brazil nut tree flowers.
D) why male orchid bees are smaller than female orchid bees.
E) the importance of orchid and Brazil nut tree flowers for the production of orchid bee honey.
Answer: B
If a female orchid bee has just left a Brazil nut tree with nectar in her stomach, and if she visits only other flowers on the same tree, the result should be
A) pollination.
B) more nectar in her stomach.
C) more pollen in her pollen basket.
D) Three of the responses above are correct.
E) Two of the responses above are correct.
Answer: E
If a female orchid bee has just left a Brazil nut tree with nectar in her stomach, and if she visits another flower on a different Brazil nut tree, what is the sequence in which the following events should occur?
1. double fertilization
2. pollen tube emerges from pollen grain
3. pollen tube enters micropyle
4. pollination
A) 4, 2, 3, 1
B) 4, 2, 1, 3
C) 4, 3, 2, 1
D) 2, 4, 3, 1
E) 2, 4, 1, 3
Answer: A
Orchid bees are to Brazil nut trees as ________ are to pine trees.
A) breezes
B) rain droplets
C) seed-eating birds
D) squirrels
E) both seed-eating birds and squirrels
Answer: A
The taller a Brazil nut tree is,
1. the more valuable it is as a source of lumber.
2. the less useful it is to harpy eagles.
3. the greater its photosynthetic rate relative to neighboring plants.
A) 1 only
B) 1 and 2
C) 1 and 3
D) 2 and 3
Answer: C
