Is the following statement true or false, and why? New adaptations do not evolve from scratch.

A) False; traits can always arise de novo.
B) False; some traits evolve from scratch, and some are modifications of previously existing traits.
C) True; new adaptations are modifications of previously existing traits.
D) none of the above

Several studies have revealed that the Eda gene fulfills the three necessary conditions for evolution by selection. Which is not one of these conditions?

A) functional importance of armor for survival
B) extensive among-individual difference in phenotype
C) inherited genetic variation underlying phenotype differences
D) genetic fixation at the Eda gene

Tracheids are ____ than vessel elements and ____ at their ends.

A) wider; do not have perforation plates
B) wider; have perforation plates
C) narrower; do not have perforation plates
D) narrower; have perforation plates
E) narrower; do not have pits

Which allele combination represents a recessive monohybrid trait?

A) aa
B) Aa
C) AA
D) ab
E) Ab

The gastric phase of gastric secretion

A) decreases the release of gastrin in the stomach.
B) is triggered by taste, sight, thought, or smell of food.
C) is mediated by impulses on sympathetic nerves.
D) leads to the greatest volume of gastric secretion.
E) leads to the least volume of gastric secretion.

Which of the following minerals is mismatched with its function?

A) Calcium - bone formation
B) Zinc - hemoglobin synthesis
C) Potassium - muscle and nerve function
D) Cobalt - erythrocyte production
E) Selenium - component of many enzymes