Which one of the following statements about the Acacia tree is/are correct? 1. It has a long shallow root system which enables it to find moisture 2. It has thorny leaves to prevent water loss 3. It has wide crown so the foliage can absorb the maximum Sunlight Select the correct answer using the code given below:
- (a)1 only
- (b)2 and 3 only
- (c)1 and 2 only
- (d)1, 2 and 3
Correct — D, 1, 2 and 3. The acacia is the standard textbook tree of hot dry lands, and all three statements describe adaptations it is described by. Its roots run long and near the surface so that a wide area of ground is tapped for the little rain that falls, which the statement calls a long shallow root system. Its leaves are reduced to thorns and small leaflets, cutting the surface from which water can evaporate. Its crown spreads wide and flat, so the small amount of foliage it does carry is spread out to catch sunlight rather than stacked in shade. Together they describe a plant solving two problems at once — hold on to water, and still gather enough light to live.
- (a)1 only — Accepts the root adaptation and rejects the other two, but the thorn and the spreading crown are as standard a part of the acacia description as the roots are.
- (b)2 and 3 only — Drops the one statement about water capture. A dry-land tree that could not reach moisture would not survive long enough for its leaf and crown adaptations to matter.
- (c)1 and 2 only — Keeps the water-saving pair and discards the light-gathering one. The flat, umbrella-like crown of the acacia is a described feature, not a distractor invented for this item.
Plants of arid and semi-arid country are xerophytes, and their adaptations fall into three families — reach water, lose less of it, and still photosynthesise. Long roots reach; reduced leaves, thick cuticles, sunken stomata and thorns conserve; a wide crown or a green stem keeps the light budget viable. The acacia is the one tree that shows all three at once, which is why examiners keep returning to it.
Read the root statement carefully — it says long and shallow, not deep. Both are true of the genus: mature acacias also send down a taproot, but the lateral roots spread far and stay near the surface, and that is what catches a brief shower before it evaporates. The statement about thorns is worth stating precisely too. The thorns are modified stipules or modified leaves; whichever the species, the effect is the same reduction in transpiring surface. As of the 2020 exam the tree was still catalogued largely under Acacia; taxonomists have since split much of the group into Vachellia and Senegalia, so a modern text may print Vachellia nilotica where an older one printed Acacia nilotica.
- Xerophytes reduce water loss by shrinking leaf area, thickening the cuticle, sinking stomata into pits and converting leaves into spines.
- Acacia roots combine a deep taproot with long lateral roots close to the surface, which together exploit both stored moisture and light rain.
- The flat, spreading acacia crown is the characteristic silhouette of savanna and thorn-forest country.
- Babool, Acacia nilotica, is the common Indian acacia of dry plains; the group also yields gum arabic and katha.
- Much of the genus has been reclassified into Vachellia and Senegalia, so the same tree appears under two names in different books.
Each statement in the question answers a different demand — get water, keep water, keep photosynthesising — so all three can be true together.
- Assuming a desert tree must have deep roots only, and rejecting the shallow-root statement.
- Expecting a select-the-correct-code item to have at least one wrong statement.
- Confusing the wide crown with dense foliage — an acacia crown is broad but thin.
Adaptation items are usually written so that every statement is textbook-true; the examiner is testing whether you can resist looking for something to reject.
Which of the following leaf modifications occurs/occur in desert areas to inhibit water loss? 1. Hard and waxy leaves 2. Tiny leaves or no leaves 3. Thorns instead of leaves Select the correct answer using the codes given below.
- (a) 1 and 2 only
- (b) 2 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer(d) 1, 2 and 3
The leaf half of this question, asked on its own. It confirms the second statement here — thorns in place of leaves are a water-saving device — and shows the same examiner habit of making every listed adaptation genuine.
Which of the following leaf modifications occur(s) in the desert areas to inhibit water loss? 1. Hard and waxy leaves 2. Tiny leaves 3. Thorns instead of leaves Select the correct answer using the code given below:
- (a) 2 and 3 only
- (b) 2 only
- (c) 3 only
- (d) 1, 2 and 3
Answer(d) 1, 2 and 3
The same three leaf adaptations repeated five years later with the options reshuffled, which is a useful reminder that the code letters move even when the content does not.
- practice — not a real PYQ
The conversion of leaves into thorns in desert plants serves mainly which one of the following purposes?
- (a)To increase photosynthesis
- (b)To reduce transpiration
- (c)To store water
- (d)To anchor the plant
Answer(b) To reduce transpiration — a thorn has almost no surface from which water vapour can escape.
- practice — not a real PYQ
Plants adapted to grow in habitats with very little available water are called
- (a)hydrophytes
- (b)halophytes
- (c)xerophytes
- (d)mesophytes
Answer(c) xerophytes — halophytes are salt-tolerant, hydrophytes are water plants and mesophytes are the ordinary intermediate group.