ISA Tree Biology & Physiology 1 — Questions and Answers
Question 1: What is the role of xylem in a tree?
- Transporting sugars to the leaves
- Transferring water from roots to leaves (Correct answer)
- Protecting the tree from pests
- Forming leaves and branches
Correct answer: Transferring water from roots to leaves
Xylem is one of the two main transport tissues in vascular plants, including trees. Its primary function is to transport water and dissolved mineral nutrients from the roots, up through the stem, and to the leaves. This upward movement is crucial for photosynthesis and maintaining turgor pressure within the plant.
Question 2: What is photosynthesis in trees?
- The absorption of water from the soil
- The process of nutrient absorption
- The conversion of sunlight into energy (Correct answer)
- The production of hormones for growth
Correct answer: The conversion of sunlight into energy
Photosynthesis is the vital process by which green plants, including trees, convert light energy into chemical energy. Using chlorophyll, carbon dioxide from the air, and water from the soil, trees produce glucose (sugar) for food and release oxygen as a byproduct. This process is fundamental for tree growth and survival.
Question 3: How does tree bark protect the tree?
- Regulates water flow
- Absorbs sunlight for energy
- Protects from pests and environmental damage (Correct answer)
- Facilitates root growth
Correct answer: Protects from pests and environmental damage
Tree bark serves as the tree's protective outer layer, shielding the delicate inner tissues from various threats. It acts as a barrier against insect infestations, fungal diseases, and physical damage from animals or weather extremes. Bark also helps regulate the tree's internal temperature and prevents excessive water loss.
Question 4: What is the function of phloem in trees?
- Transporting water from roots to leaves
- Transferring sugars and nutrients from leaves (Correct answer)
- Protecting the tree from diseases
- Regulating water absorption
Correct answer: Transferring sugars and nutrients from leaves
Phloem is the other main transport tissue in trees, working in conjunction with xylem. Its primary role is to transport sugars (produced during photosynthesis in the leaves) and other organic nutrients to all parts of the tree where they are needed for growth or storage. This movement can be both upwards and downwards, depending on the plant's needs.
Question 5: How do trees adapt to drought conditions?
- Increase transpiration
- Reduce leaf growth (Correct answer)
- Increase photosynthesis
- Absorb more CO2
Correct answer: Reduce leaf growth
Trees adapt to drought conditions by implementing strategies to conserve water. Reducing leaf growth, shedding leaves, or developing smaller, thicker leaves are common adaptations that minimize the surface area available for transpiration (water loss through leaves). This helps the tree retain precious water during periods of scarcity.
Question 6: What is the primary function of tree roots?
- Storing excess water
- Producing chlorophyll
- Anchoring and absorbing nutrients (Correct answer)
- Generating oxygen
Correct answer: Anchoring and absorbing nutrients
Tree roots perform two critical functions for the tree's survival. Firstly, they anchor the tree firmly in the soil, providing stability against wind and other forces. Secondly, and equally important, they absorb water and essential mineral nutrients from the soil, which are then transported to the rest of the tree.
Question 7: What is transpiration in trees?
- Absorbing water from the soil
- Releasing water vapor through leaves (Correct answer)
- Producing sugars for growth
- Forming new roots
Correct answer: Releasing water vapor through leaves
Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released into the atmosphere. This process is essential for pulling water up from the roots and helps cool the plant, but excessive transpiration can lead to water stress.
Question 8: What is the impact of soil compaction on tree roots?
- Improves water retention
- Enhances root growth
- Reduces root oxygen and water absorption (Correct answer)
- Increases photosynthesis
Correct answer: Reduces root oxygen and water absorption
Soil compaction, often caused by heavy foot traffic or machinery, reduces the pore space within the soil. This decrease in pore space limits the availability of oxygen for root respiration and impedes water infiltration and absorption. Compacted soil can severely stress tree roots, leading to poor growth and overall tree decline.
Question 9: What is cambium tissue in a tree?
- Old growth tissue
- Newly forming leaf buds
- Active growth tissue (Correct answer)
- Water-transporting cells
Correct answer: Active growth tissue
The cambium is a thin layer of actively dividing cells located between the xylem and phloem in a tree's stem and roots. This meristematic tissue is responsible for secondary growth, producing new xylem (wood) towards the inside and new phloem towards the outside, allowing the tree to increase in girth. It is the primary growth engine for the tree's diameter.
ISA Tree Biology & Physiology 1
What is the role of xylem in a tree?