AP BIOLOGY

Detailed explanation-1: -Solution: Small leaves in pteridophytes are known as microphylls. Larger leaves are known as macrophylls. A is a microphyll with a single unbranched vein and is connected to the stem without a stalk. B is a macrophyll with multiple branched veins and is connected to the stem with a stalk.

Detailed explanation-2: -Some Pteridophytes have small leaves called microphylls (e.g lycopodium) and some have large leaves called megaphylls (e.g Pteris). Leaves may also have spores on the underside. Such leaves are called sporophylls. Plants are flowerless and seedless.

Detailed explanation-3: -Megaphylls are the large leaves that some pteridophytes have. For example, fern plants. The main plant bears the sporangia. These bear some leaf-like appendages called the sporophylls.

Detailed explanation-4: -Microphylls are defined as leaves of small size, with simple venation (one vein) and associated with steles that lack leaf gaps (protosteles). By contrast, megaphylls are defined as leaves of generally larger size, with complex venation and associated with leaf gaps in the stele [3].

Detailed explanation-5: -Some of the general illustrations of microphyllous pteridophytes are Selaginella, Psilotum, Lycopodium, Isoetes, Equisetum and so on. Ferns symbolize a much more specialized class of higher pteridophytes with larger leaves (i.e., megaphyllous).