Endosperm tissue arises by the fusion of a sperm nucleus with two nuclei of the:
A. male gametophyte
B. female style
C. ovule wall
D. female egg
E. female gametophyte central cell
E. female gametophyte central cell
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Endosymbiosis is an evolutionary theory that explains the origin of eukaryotes and suggests a specific order in which this might have occurred. Ancestral cells engulfed and then began to use the metabolic processes of the smaller cells
Based on shared core processes and features, which statement most accurately describes the order, the theory and the evolutionary implications for all organisms within domain Eukarya? A) Ancestral heterotrophic eukaryotes most likely engulfed both a heterotrophic and an autotrophic prokaryote, whereas ancestral photosynthetic eukaryotes probably provided the host cell for the first mitochondria. Over time, natural selection favored these relationships and these cells became ancestors of all eukaryotes. B) All ancestral eukaryotes would have most likely consumed a nucleus-like prokaryote that eventually became the eukaryotic nucleus. These new eukaryotic cells would have had an advantage over prokaryotic cells by acquiring a nuclear command center for regulating cellular activities. C) As carbon dioxide levels were increasing over time, natural selection would have favored organisms that acquired a photosynthetic prokaryote to convert carbon dioxide into sugars. These would have likely been the first eukaryotic cells. At which point, these ancestral cells engulfed mitochondria-like prokaryotes that would have provided an even greater advantage for cells in this environment. D) As Earth was becoming more aerobic, mitochondria would have provided an advantage to host cells by converting "toxic" oxygen into energy for heterotrophic cells. Since mitochondria are found in all eukaryotes, these combinations likely evolved first. Photosynthetic eukaryotes probably acquired an autotrophic prokaryote, which developed an advantageous symbiotic relationship with the host cell.
You are working in a zoo, and unbeknownst to the zoo-keepers, a male lion sneaks into the pen of a female tiger, and months later, the female tigers gives birth to a liger. Lions and tigers do not co-exist in the wild, so ligers are not found naturally. This liger looks more like the father lion than the mother tiger because the lion genes tend to be more dominant, but it is larger than either the mother or the father. However, the liger is sterile, and so the only way to create more ligers is to continually breed male lions to female tigers. When the liger is presented to the scientific community, it is decided that the liger is not a new species. Upon which species concept is this decision based?
A. Biological species concept B. Morphospecies concepts C. Phylogenetic species concept D. Sympatric species concept
In which vertebrate group are there two atria but only a single ventricle?
A) Some reptiles B) Crocodiles C) Birds D) Fishes E) Mammals
How many times more acidic is a solution with a pH of 3 than a solution with a pH of 6?
A. 10 B. 1000 C. 36 D. 63 E. 3