Exam 38: Angiosperm Reproduction and Biotechnology

In America, a summer occupation in the Corn Belt states is de-tasselling the corn: removing unwanted male flowers so that female flowers on the same plant are pollinated by the desired pollen for the hybrid corn. What does this tell you about corn? The flowers are ________.

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 metres tall, is a source of high-quality timber, and is a favourite 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. Brazil nuts are composed primarily of endosperm. About $50 million worth of nuts are harvested each year. Scientists have discovered that the pale yellow flowers of Brazil nut trees cannot fertilise themselves and admit only female orchid bees as pollinators. 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 inside the fruit, which moisture can now enter. The uneaten seeds may subsequently germinate. The same bees that pollinate the flowers of the Brazil nut trees also 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 ________.

Some dioecious species have the XY genotype for male and XX for female. After double fertilisation, what would be the genotypes of the embryos and endosperm nuclei?

Fruit ripening represents an example of positive feedback. Which one of the following statements accurately justifies why the process of fruit ripening involves positive feedback?

If an ovary contains 50 ovules, what is the minimum number of pollen grains that must land to form 50 mature seeds?

Which of the following is the correct order of floral organs from the outside to the inside of a complete flower?

In a typical angiosperm, what is the sequence of structures encountered by the tip of a growing pollen tube on its way to the egg? 1) micropyle 2) style 3) ovary 4) stigma

In a typical dicot ovule, a surviving megaspore divided by ________ consecutive mitotic divisions without cytokinesis results in ________ nuclei.

In which of the following pairs are the two terms equivalent?

Which of the following would be the most problematic for the natural environment in the development of genetically engineered crops?

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 metres tall, is a source of high-quality timber, and is a favourite 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. Brazil nuts are composed primarily of endosperm. About $50 million worth of nuts are harvested each year. Scientists have discovered that the pale yellow flowers of Brazil nut trees cannot fertilise themselves and admit only female orchid bees as pollinators. 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 inside the fruit, which moisture can now enter. The uneaten seeds may subsequently germinate. Animals that consume Brazil nuts derive nutrition mostly from tissue whose nuclei have how many chromosomes?

Retaining the zygote on the living gametophyte of land plants ________.

Sperm cells are formed in plants by ________.

Which of these is a major trend in land plant evolution?

What adaptations should one expect of the seed coats of angiosperm species whose seeds are dispersed by frugivorous (fruit-eating) animals, as opposed to angiosperm species whose seeds are dispersed by other means? 1) The exterior of the seed coat should have barbs or hooks. 2) The seed coat should contain secondary compounds that irritate the lining of the animal's mouth. 3) The seed coat should be able to withstand low pHs. 4) The seed coat, upon its complete digestion, should provide vitamins or nutrients to animals. 5) The seed coat should be resistant to the animals' digestive enzymes.

Over human history, which process has been most important in improving the features of plants that have long been used by humans as staple foods?

Double fertilisation in angiosperm embryo sac produces endosperm, a food-storing tissue of the seed. The genetic makeup of endosperm is ________.

Which of the following is a true statement about asexual reproduction in plants?

Which of the following could be considered an evolutionary advantage of asexual reproduction in plants?

The egg of a plant has a haploid chromosome number of 12 (n = 12). What is true about the number of chromosomes in the cells of other tissues of this plant?