Question Video: Explaining How Depositing Gum Can Help Defend a Plant Against a Pathogen | Nagwa Question Video: Explaining How Depositing Gum Can Help Defend a Plant Against a Pathogen | Nagwa

Question Video: Explaining How Depositing Gum Can Help Defend a Plant Against a Pathogen Biology • Third Year of Secondary School

Plants that have wounds or damage to their exterior may deposit gums. Why is this considered a defense against pathogens?

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Video Transcript

Plants that have wounds or damage to their exterior may deposit gums. Why is this considered a defense against pathogens? (A) The secretion of gums encourages the development of structural defenses like thorns. (B) The secretion of gums can trap pathogens and prevent them from entering the plant. (C) The secretion of gums can initiate the hypersensitive response, which causes rapid cell death around the site of infection. (D) This statement is incorrect because gums only help defend the plant against herbivores, not pathogens.

We are being asked how a plant depositing gums on an outside wound could be considered a defense against pathogens or germs. To answer this, let’s review what effect the deposition of gums has on the wounded bark of a tree. When a plant’s outer tissues are damaged, gums and resins flow out of the plant. These are initially very thick liquids. And as they flow out, they create a covering over the entire damaged surface area. Then as they dry, they harden but remain sticky.

Imagine a pathogen trying to enter the plant’s tissues through the damaged area. Not only do the gums create a physical blockage that would prevent a pathogen from being able to easily enter through the wound, but they are also sticky. So any pathogens that attempt to enter will likely get stuck to or within the gum and essentially be trapped there. So gums provide defense both by creating a physical blockage and by trapping pathogens within their stickiness.

Therefore, the correct answer must be (B). The secretion of gums can trap pathogens and prevent them from entering the plant.

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