50) Which of the following would be the most problematic for the natural environment in the
development of genetically engineered crops?
A) the introduction of male sterility into crops
B) the creation of transgenic crops with apomictic seeds
C) the creation of crops with flowers that develop normally, but fail to open
D) the creation of transgenic crops that hybridize more easily
51) 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?
A) Once seeds have reached maturity, chemical signals increase enzymatic activity in fruit to
convert sugars into starches, thicken pulp, and maintain color in the fruit.
B) Once seeds have reached maturity, chemical signals block enzymatic steps that normally
convert sugars into starches and sugars accumulate from photosynthetic activity within the fruit.
C) Chemical signals initiate a process that triggers enzymatic activity, which involves converting
starches into sugars, softening of pulp, and color change of fruit.
D) Chemical signals shut down enzymatic activity within the fruit, which results in breakdown
of starches into sugars, softening of pulp, and color change of fruit.
52) In order for an ovule (egg cell) in a flower to be fertilized and form a viable seed, pollination
must occur. In this process, a sperm cell is delivered to the ovule when the pollen grain lands on
the stigma and grows a tube, which enters the ovary and discharges the sperm cell to form a
diploid zygote when it fuses with the egg cell. Although it only takes one pollen grain to
successfully deliver sperm to the egg, numerous pollen grains are generally transferred to the
stigma during insect pollination of flowering plants. Which phenotypic traits of pollen would you
predict to be selected upon to promote survival and fitness within an insect-pollinated flowering
plant?
A) High pollen tube growth rate and ability to detect chemicals from cells surrounding the egg.
B) Ability to produce the most cells during mitotic growth of the pollen tube.
C) Elaborate and striking UV “nectary guides” on the petals to guide an insect to the stigma.
D) Larger pollen in order to carry the tube that is necessary for delivery of the sperm cells.