Question

questions 1-10 of 10 | page 1 of 1
question 1 (1 point)
vascular wilt pathogens cause damage by blocking the xylem, which prevents water movement within the plant.
☐ true
☐ false

question 2 (1 point)
phytoalexin production requires the plant to undergo a genetic mutation to change its dna expression.
☐ true
☐ false

question 3 (1 point)
waterlogging primarily causes stress by washing away essential nutrients from the soil.
☐ true
☐ false

question 4 (1 point)
what is the \growth-defense trade-off\ observed in plants?
☐ a energy allocated to defense mechanisms is energy taken away from growth and reproduction
☐ b plants grow larger when they have more pests to fight off
☐ c plants with high growth rates are naturally resistant to all diseases
☐ d plants stop growing entirely once they are infected by a pathogen

question 5 (1 point)
identify whether the following scenarios involve abiotic (non-living) or biotic (living) stress factors by writing the correct classification next to each description.
column a
1 ____ a fungal pathogen (hemibiotroph) that kills host cells to extract nutrients
2 ____ high soil salinity levels that cause osmotic stress and ion toxicity in the roots
3 ____ invasive weed species aggressively competing with crops for light and soil nutrients
4 ____ hypoxia (low oxygen) in low root zones caused by excess water displacing air in soil pores.
5 ____ a population of herbivorous insects removing leaf surface area and creating open wounds
6 ____ extreme temperature events, such as heat waves, that damage essential cellular structures.
column b
a. biotic
b. abiotic

question 6 (1 point)
which of the following describes a \biotroph\ pathogen?
☐ a an organism that feeds on living tissue (e.g., powdery mildews)
☐ b an organism that chews on leaf margins
☐ c an organism that blocks water transport in the xylem
☐ d an organism that kills cells immediately (e.g., botrytis)

question 7 (1 point)
invasive weeds act as biotic stressors by competing for resources like light, nutrients, and water.
☐ true
☐ false

question 8 (1 point)
when a plant experiences drought stress, it closes its stomata to conserve water. what is the unintended negative consequence of this action?
☐ a it prevents the plant from absorbing sunlight
☐ b it allows excess sodium to enter the roots
☐ c it causes immediate root rot due to lack of oxygen
☐ d it stops co₂ intake, halting photosynthesis

question 9 (1 point)
a farmer observes tomato plants wilting and leaves curling upward after a week of record-breaking heat and rain. which factor is primarily responsible?
☐ a damage caused by tinned bacteria
☐ b biotic attack from a fungal pathogen
☐ c abiotic stress from soil saturation
☐ d abiotic stress from heat and drought

question 10 (1 point)
high soil salinity causes \physiological drought.\ what does this mean?
☐ a the salt blocks the plants root structures
☐ b osmotic stress makes it difficult for roots to pick water up against a water potential gradient
☐ c the salt physically dries out water from the soil
☐ d the accumulation of salt within the plant leads to leaf burn

Explanation:

1. Vascular wilt pathogens block the xylem, stopping water/nutrient movement in plants.
2. Phenotypic plasticity is non-genetic trait change due to environment, not mutation.
3. Waterlogging harms plants by depriving roots of oxygen, not leaching nutrients.
4. The growth-defense trade-off means plants divert energy from growth/reproduction to defense mechanisms.
5. Biotic stress comes from living organisms; abiotic stress comes from non-living environmental factors.
6. A biotroph feeds on living host tissue without killing it immediately.
7. Weeds are living organisms, so they are biotic (not abiotic) stressors.
8. Closing stomata to conserve water stops CO₂ intake, halting photosynthesis.
9. Wilting and leaf curling from poor water uptake is a response to water deficit (heat/drought).
10. High soil salinity creates hyperosmotic stress, making it hard for roots to take up water via osmosis.

Answer:

1. True
2. False
3. False
4. a. Energy allocated to defense mechanisms is energy taken away from growth and reproduction
5. 1. b. Biotic
6. a. Abiotic
7. b. Biotic
8. a. Abiotic
9. b. Biotic
10. a. Abiotic
11. a. An organism that feeds on living tissue (e.g., powdery mildews)
12. False
13. d. It stops CO₂ intake, halting photosynthesis
14. d. Abiotic stress from heat and drought
15. b. Osmotic stress makes it difficult for roots to pick water up against a water pressure gradient