Clustering of genes with related functions on the same chromosome reflects the fact that many genes arose through the process of duplication of a single gene, followed by divergence
A. true
B. false
A
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The following steps refer to various stages in transmission at a chemical synapse
1. Neurotransmitter binds with receptors associated with the postsynaptic membrane. 2. Calcium ions rush into neuron's cytoplasm. 3. An action potential depolarizes the membrane of the presynaptic axon terminal. 4. The ligand-gated ion channels open. 5. The synaptic vesicles release neurotransmitter into the synaptic cleft. Which sequence of events is correct? A) 1 ? 2 ? 3 ? 4 ? 5 B) 2 ? 3 ? 5 ? 4 ? 1 C) 3 ? 2 ? 5 ? 1 ? 4 D) 4 ? 3 ? 1 ? 2 ? 5 E) 5 ? 1 ? 2 ? 4 ? 3
Male peacocks have tail feathers that make up about 60% of their body length. During the mating season they shake these feathers in front of females
Longer feathers produce a larger volume of rustling sound for a given shaking rate, but they are also heavier, and thus require more energy to shake at a given rate than shorter feathers. This suggests that ______________. A. selective pressures will continue selection for longer and longer peacock tails B. selective pressures will always result in shorter peacock tails to reduce the energetic cost of shaking C. there are selective pressures against too long or too short of a tail, which results in the variable tail lengths D. tail length is completely random because there are selective pressures both for and against longer tails
Weeks of depressing work in the botany lab have culminated in yet another unsuccessful attempt to germinate your seeds. You are down to three batches of carefully packed seeds (you started with ten), and not one seedling to show for your work. Head in hands, you consult with a colleague from the California lab who sent the seeds earlier in the year. He makes a crazy recommendation but you brush it off because this colleague always has wild ideas. Later, in desperation, you decide to do it. Following his instructions carefully, you set fire to the seed packet and then put out the controlled blaze you have created. Six weeks later, you are carefully tending the seedlings and berating yourself for not having listened to him sooner. Of course! Which biome are these seeds from after all?
a. arctic tundra b. boreal forest c. chaparral d. temperate forest
A cell releases chemical signals into its surrounding space in order to communicate with neighboring cells. Which of the following must occur for the communication to be successful?
A) The chemical signal must bind to hormones on the neighboring cells B) The same chemical signal must be produced within the neighboring cells C) The neighboring cell must have the receptor to receive the signal