Dietary supplements and decongestants containing ephedrine have recently become more strongly regulated in the United States. Which phylum contains the plant from which ephedrine is extracted?

Six major crops˜wheat, rice, maize, potatoes, cassava, and sweet potatoes˜contribute disproportionately to human diets. What percentage of all the calories consumed by humans is supplied by these crops?

Which of the listed examples is evidence provided by living gymnosperms of an evolutionary transition between seedless and seed plants?

Which of the following best states the advantages that seeds have over spores?

Which gymnosperm phylum is characterized by large cones and fern-like leaves and thrived during the Mesozoic?

What global change occurring between the Carboniferous period and the Permian period likely contributed to the success of the gymnosperms?

What is located in the scalelike structures packed densely in pollen cones?

Each pollen grain of a gymnosperm contains a __________.

In ovulate cones, megasporocytes undergo __________ and produce __________ megaspores.