Linen is woven from strands of sclerenchyma ________ that occur in the phloem of flax (Linum spp.).
A. sieve
B. collenchyma
C. sclerid
D. fiber
E. tracheid
Answer: D
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Zip1 is a protein in yeast that is required for synaptonemal complex formation. Assuming synaptonemal complexes are required for meiosis in yeast, where do you predict these cells arrest (stop progressing through meiosis)?
A. Prometaphase of meiosis I B. Metaphase of meiosis I C. Metaphase of meiosis II D. Between the zygotene and pachytene stages E. Diakinesis
Which of the following would most likely result in a bottleneck event, why?
A. A small population of geese migrates and joins a large nesting flock of the same species. This is a bottleneck event because the small population do not bring in any new alleles to the large flock. B. A mutation occurs in an individual poison ivy plant, doubling the number of seeds it produces. This is a bottleneck event because even though the mutation is passed down to the next generations, it does not change the frequency of any other alleles in the population. C. A hurricane blows through a coastal swamp, killing 98% of the snails in a population. This is only a bottleneck event if there is a change in the number of alleles in the population. The 2% of the snails remaining still have the same allele frequencies as the total population. D. A large population of broomsedge grass in a field is determined to be in Hardy-Weinberg equilibrium. This is a population bottleneck event because there is no random mating going on which increases the likelyhood that there will be a decrease in the number of alleles in the population. E. A small population of ducks with red beaks join a large population of ducks that have no red beaks. After 5 generations the number of ducks with red beaks is reaching 50% in the population. This is a bottleneck event because there is a decrease in the number of ducks without red beaks.
Biologists believe that whooping cranes suffer from a high rate of developmental deformities of the spine and trachea
because of ____.
a. biological magnification of DDT b. exposure to hormone-mimicking pollutants from plastics c. a population bottleneck and loss of genetic variability d. conservation biologists saving chicks that would have died at hatching e. exposure to PCBs used as insulators in electronics
What do the fossil records tell us about hominins?
A) Hominins were a series of species, with one set of branches that eventually led to modern humans. B) Hominins were related to chimpanzees but not to humans. C) Hominins were a diverse group of human ancestors not related to other primates. D) Hominins were a diverse group of primate species with modern humans as the only surviving group.