Which phylum includes animals that lack tissues?
cnidaria
porifera
platyhelminthe...
Biology, 16.09.2019 12:20 tpsavage9755
Which phylum includes animals that lack tissues?
cnidaria
porifera
platyhelminthes
arthropoda
chordata
Answers: 2
Biology, 21.06.2019 15:30
Which of the following will not cause mass extinction? a. drastic change is weather b. geological change c. both a and b d. none of the above
Answers: 2
Biology, 22.06.2019 20:30
Our planet has experienced five major extinctions in the four billion year history of life. the first, 450 million years ago, occurred shortly after the evolution of the first land-based plants and 100 million years after the cambrian explosion. the second extinction occurred 350 million years ago, causing the formation of coal forests. next earth experienced two mass extinctions during the triassic period, between 250 and 200 million years ago. the fifth mass extinction occurred 65 million years ago, ending the reptilian dominance of the earth. according to richard leakey, the sixth mass extinction is happening right now. leakey suggests that we, the human race, are the cause. each year, at our hand, approximately 50,000 species vanish from earth. he believes that man is destroying earth at a rate comparable with the impact of a giant asteroid. leakey's statistics indicate that 50% of earth's species will become extinct within the next 100 years assuming leakey's hypothesis of a sixth mass extinction to be true, how will we expect the model to change? a) a sharp spike in the graph approximately 100 million years from now b) a dip in the graph, followed by a sharp spike about 100 million years from now c) a sharp spike in the graph immediately following the "0" location of the x axis d) a plateau following the "0" mark on the x axis, followed by a gradual rise to a new peak
Answers: 3
Biology, 23.06.2019 05:30
Rank the following one-base point mutations (from most likely to least likely) with respect to their likelihood of affecting the structure of the corresponding polypeptide: 1. insertion mutation deep within an intron 2. substitution mutation at the third position of an exonic codon 3. substitution mutation at the second position of an exonic codon 4. deletion mutation within the first exon of the gene a) 1, 2, 3, 4 b) 4, 3, 2, 1 c) 2, 1, 4, 3 d) 3, 1, 4, 2 e) 2, 3, 1, 4
Answers: 2
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