What is the correct sequence of steps during infection of plants by nitrogen-fixing bacteria?
A) Rhizobia release Nod factors; roots release flavonoids; rhizobia proliferate inside of root hair; infection thread grows into the root cortex; nodule forms.
B) Rhizobia release flavonoids; roots release Nod factors; rhizobia proliferate inside of root hair; infection thread grows into the root cortex; nodule forms.
C) Roots release flavonoids; rhizobia release Nod factors; rhizobia proliferate inside of root hair; nodule forms; infection thread grows into the root cortex.
D) Roots release flavonoids; rhizobia release Nod factors; rhizobia proliferate inside of root hair; infection thread grows into the root cortex; nodule forms.
E) Nodule forms; infection thread grows into the root cortex; rhizobia proliferate inside of root hair; rhizobia release flavonoids and Nod factors.
Answer: D
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When the concordance rate of a trait is significantly higher in identical twins than it is in fraternal twins, we can conclude that:
A. the trait has a strong genetic component. B. the trait has a strong environmental component. C. the trait has a strong genotype-byenvironment interaction. D. the trait has a strong norm of reaction. E. the trait has both a strong genetic component and a strong norm of reaction.
When gibberellin binds to its receptor, what happens to activate the gibberellin-dependent transcription factor GA-TRXN?
A. Ethylene is released. B. A ubiquitin tag is used to degrade the GA-TRXN inhibitor. C. A DELLA protein is degraded, freeing the GA-TRXN. D. A DELLA protein is attached to GA-TRXN to activate it. E. The gibberellin is transferred to an alternate binding site.
Which of the following organelles is not generally found in animal cells?
A) food vacuole B) centriole C) endoplasmic reticulum D) central vacuole E) mitochondrion
What organelles transport proteins through the cell?
A. Lysosomes B. Ribosomes bound to rough endoplasmic reticulum C. Golgi apparatus D. Vesicles