Describe the major differences and similarities between gymnosperms and angiosperms
What will be an ideal response?
Gymnosperms and angiosperms both produce seeds, specialized structures for protecting the
developing sporophyte embryo from drying out and other dangers. Gymnosperms and angiosperms
also produce gametophytes that develop within protective tissues in the sporophyte. Gymnosperms and
angiosperms make pollen grains, specialized male gametophytes that are protected from drying out
and that do not need external water to reach an egg. All of these adaptations allow gymnosperms and
angiosperms to generally live in dry conditions. Angiosperms differ significantly from gymnosperms
in many ways. Angiosperms have enhanced xylem and phloem that provide more efficient transport of
water and nutrients. Angiosperms have enhanced nutrition for embryos, with double fertilization that
produces a unique triploid endosperm to nourish the embryo. They have flowers that often attract
animal pollinators, providing more efficient means for pollination. Also, angiosperms have ovaries,
tissues that shelter the ovule from desiccation and attack. Ovaries typically develop into fruits that can
help protect seeds as well as aid in seed dispersal.
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Why is nonhomologous end joining (NHEJ) more frequent in eukaryotes?
A. Bacteria replicate frequently and so can use recombination repair to repair most double-strand breaks. B. The period of time between DNA synthesis events is longer so double-strand breaks occurring outside of the period require NHEJ. C. NHEJ is a mutagenic process that is tolerated better in larger genomes. D. Some eukaryotic cell types use NHEJ as a source of gene variation. E. All of the choices given are correct.
As a transitional form, Archaeopteryx is important because it provides insight into
a. the evolution of birds into reptiles. b. the relationship between dinosaurs and birds. c. adaptations for animals moving from an aquatic to a land environment. d. all of these
Keystone species are those that ________
a. modify the pioneer environment, allowing subsequent stages in succession to occur b. after introduction, become established and disruptive to the native structure of a community c. have a disproportionate effect on a community relative to their abundance d. provide the photosynthetic plant base necessary to all communities
What genotype would be found in an individual who is a carrier for a recessive genetic disorder but does not have symptoms of the disorder?
A) heterozygous B) homozygous for the recessive allele C) homozygous for the dominant allele D) either homozygous for the recessive allele or heterozygous