Pre AP Biology -ECO 4.2 Symbiosis- MCQ Exam Style Questions -New Syllabus
Pre AP Biology -ECO 4.2 Symbiosis- MCQ Exam Style Questions – New Syllabus 2025-2026
Pre AP Biology -ECO 4.2 Symbiosis- MCQ Exam Style Questions – Pre AP Biology – per latest Pre AP Biology Syllabus.
▶️ Answer/Explanation
The correct option is a. parasites.
Haustorial roots, also known as sucking roots, are specialized structures found in parasitic plants.
These roots penetrate the host plant’s tissues to reach the vascular system.
They establish a connection with the host’s xylem and phloem.
This allows the parasite to absorb water, minerals, and organic nutrients directly from the host.
Examples include Cuscuta (Dodder) and Viscum (Mistletoe).
Unlike epiphytes, which only use hosts for physical support, parasites rely on them for survival.
▶️ Answer/Explanation
The correct answer is b. dodder.
Dodder is a holoparasitic plant that lacks chlorophyll and cannot perform photosynthesis.
It uses specialized structures called haustoria to penetrate the host plant’s vascular system.
Through these haustoria, it extracts water, minerals, and organic nutrients directly from the host.
The cobra lily is carnivorous, not parasitic, as it makes its own food but traps insects for nitrogen.
Most orchids are epiphytes, meaning they grow on other plants for support but do not steal nutrients.
The snow plant is a mycoheterotroph, obtaining nutrients from fungi rather than directly parasitizing a plant.
▶️ Answer/Explanation
The correct option is b.
Wrapping the plant in clear plastic creates a humid microenvironment that traps water vapor.
As the humidity inside the plastic wrap reaches $100\%$, the concentration gradient of water vapor between the leaf and the air disappears.
This significantly decreases the rate of transpiration, helping the plant conserve water.
Low light and temperature further reduce the metabolic demand and evaporation rates.
Since the plastic is clear, some light enters, so photosynthesis may slow down but will not necessarily stop.
Stomata generally close, not open, when guard cells lose turgor or in response to low light.