A thick, waxy leaf cuticle usually slows the absorption of a translocated herbicide.

A thick, waxy leaf cuticle usually slows the absorption of a translocated herbicide.

• A. speeds up
• B. has no effect on
• C. slows down
• D. increases absorption dramatically

Answer: (C)

The leaf surface’s waxy cuticle acts as a barrier to chemical entry. When that cuticle is thick, it presents a tougher barrier for a translocated herbicide to cross, so the herbicide enters the leaf tissues more slowly. Since systemic movement depends on the herbicide being absorbed into the leaf and then moved through the plant, a thicker cuticle reduces the uptake rate rather than increasing it. So absorption is slowed down. Saying it speeds up, has no effect, or increases absorption dramatically would ignore the barrier role of the waxy cuticle.

The leaf surface’s waxy cuticle acts as a barrier to chemical entry. When that cuticle is thick, it presents a tougher barrier for a translocated herbicide to cross, so the herbicide enters the leaf tissues more slowly. Since systemic movement depends on the herbicide being absorbed into the leaf and then moved through the plant, a thicker cuticle reduces the uptake rate rather than increasing it. So absorption is slowed down. Saying it speeds up, has no effect, or increases absorption dramatically would ignore the barrier role of the waxy cuticle.