What is the benefit of having an inducible chemical defense, as opposed to a con
ID: 99517 • Letter: W
Question
What is the benefit of having an inducible chemical defense, as opposed to a constitutive chemical defense? (an inducible defense is when the chemical is produced when herbivory is taking place as opposed to a constitutive defense where the chemical is always present) A. Inducible chemical defense best deters herbivory. B. With inducible defense predation will take place before a defense compound is produced which means there is damage to the plant before a defense is employed. C. With inducible defense herbivores are deterred even if no defense compound is produced. D. With inducible defenses energy is conserved by only producing secondary compounds when needed instead of continually. Morphological Defenses: What type of herbivore would leaf hairs (fuzzy leaves) defend against as compared to large thorns? A. If the herbivore is small, hairs would prevent it from getting to the plant surface. B. Hairs would deter herbivores that can fly. C. Hairs will deter larger animals and thorns will deter smaller herbivores such as insects. D. Although many large herbivores would be deterred by leaf hairs, some small herbivores may also be deterred if this defense is combined with a smooth waxy surface. Mutualism with Ants: There are costs and benefits to a plant that provides housing but no food for the ants compared to a plant that provides housing and food. What is a cost to the plant that does not provide food? A. A cost is that the plants not providing food would need to grow taller to reduce herbivory. B. The cost to the plant that does not make food for the ants is the energy saved by not having to make food. C. The plant may also gain resources as a carbon sources will be brought to it by the ants which would be a cost to the plant. D. If food is not provided to the ants they will need to go off of the plant to forage for food reducing the plants defenses. E. The ants will starve and not be able to defend the plant. ADAPTATIONS FOR GAINING RESOURCES IN LOW NUTRIENT ENVIRONMENTS Symbiotic relationships with Nitrogen-fixing Bacteria: Rhizobium bacteria normally inhabit the soil. Suggest why nodules are found on the stems of Sesbania? A. The roots of the Sesbania are often underwater or in flooded soils that do not contain much N_2. B. Bacteria live best above the ground. C. Sesbania only use the nitrogen in the upper portion of the plant so they do not need to make nodules on their roots. D. Bacteria will drown under water.Explanation / Answer
1. D
In constitutive chemical defense of plants against stress caused by herbivores, the plant has ready stock of chemicals already present and are not produced after the stress.
Some egs are:- xanthotoxin, calotropin, bismorphine.etc.
In inducible chemical defense, response in the form of chemicals is produced and then released only after stress caused by herbivores to plants. It gives some degree of resistance during second encounter by same
2.B
Mechanical defense is the first line of defense by plants against herbivores. Leaf hairs are specialised epidermal cells which are present on airy plant parts. They can provide both chemical and physical defense against non vertebrate insects , which can fly.
3.D
In mutualism of plants with ants. Plants give ants space to live and food in the form of nectar and various juices.
In turn ants help plants in seed dispersal. And also indirectly protect the plant from grazing herbivores. This is known as facultative defense.
4.A
In symbiotic relationship of plants and nitrogen fixing bacteria both are benefitted.
Since plants cannot use Nitrogen present in soil in the form of N2. These bacteria convert N2 into ammonia, which can be assimilated by the plants, and thus can use them to form amino acids.
And plants provide bacteria with food in form of carbohydrates produced during photosynthesis. And also gives them space to live .
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