Problem 25 - Objective Biology for NEET

Question

Select the incorrect statement from the following: (1) A watermelon has over 92 per cent water. (2) Most herbaceous plants have only about \(10-15 \%\) of its fresh water as dry matter. (3) Woody parts of the plant have very little water. (4) Sced is without water. (5) Mature corn plant absorbs almost three litres of water per day. (6) Mustered plant absorbs water epical to its own weight in about 5 hours. (a) All cxcept 6 (b) All cxcept 5 (c) Only 4 (d) Only 3

Step-by-Step Solution

Answer

The incorrect statement is 'Sced is without water.' The answer is (c) Only 4.

Step 1: Identifying Statements

The given options consist of 6 statements. A close reading of these statements is required to understand their meaning.

Step 2: Verifying Statement 1

Watermelon is known for high water content. Therefore, stating that Watermelon has over 92% water is true.

Step 3: Verifying Statement 2

Herbaceous plants tend to have low amount of dry matter in relation to fresh weight, typically around 10-15%. This statement is therefore true.

Step 4: Verifying Statement 3

Woody parts of plants are known to have less water compared to other parts. This statement is generally true, though it may vary depending on the types of plant.

Step 5: Verifying Statement 5

A mature corn plant does absorb considerable amount of water, approximately around three litres per day. This statement is true.

Step 6: Verifying Statement 6

Mustard plants do absorb water en masse. This statement also seems to hold true.

Step 7: Verifying Statement 4

Statement 4 mentions a 'Sced', which is not recognized in botany. Therefore, it cannot hold water, making this statement incorrect.

Key Concepts

Plant Water Content

Plants largely consist of water, which is essential for their growth, metabolism, and physiological processes. Water plays several critical roles in plants: it maintains cell turgor, drives photosynthesis, enables nutrient transport, and helps in temperature regulation.

Different plants have varying water content based on species and parts of the plant. For instance:

• Fresh fruits and vegetables, like watermelon, have high water content that can be more than 90%.
• Herbaceous plants, which are non-woody, tend to have a significant proportion of water relative to their mass.
• The woody parts of a plant, such as stems and branches, generally contain less water.

Understanding water content is important for agriculture and horticulture as it affects storage, nutritional value, and palatability of plant products.

Herbaceous Plants

Herbaceous plants are characterized by their non-woody stems that are often green and soft. They are distinct from woody plants, which have hardened stems. These plants typically contain high water content, ensuring flexibility and growth efficiency.

Traits of herbaceous plants:

• They usually grow quickly and have a life cycle ranging from seasonal to perennial.
• Include a wide variety of species such as flowers, vegetables, and ferns.
• Have a low proportion of dry matter, which is often only 10-15% of their fresh weight.

This high water content is advantageous during favorable conditions but may make them susceptible to dehydration during droughts or excessive heat.

Woody Plants

Woody plants, like trees and shrubs, have strong and rigid structures. Their main feature is the presence of lignified tissues, which gives them their woody characteristics, allowing them to stand tall and grow large.

Some features of woody plants include:

• The woody parts, such as the trunk and branches, have relatively low water content compared to leaves and fruits.
• They grow slowly and live longer than many herbaceous plants, often for decades or centuries.
• Common examples include oak trees, pines, and rose bushes.

While they contain less water in their woody parts, they store vital water reserves necessary for survival in unfavorable conditions.

Seed Water Content

Seeds, in their mature state, are generally low in water content. This is an adaptation that allows them to resist adverse conditions and remain viable for long periods before germination.

Important aspects about seed water content:

• Seeds start with higher water content during development but dry considerably as they mature.
• This low water content helps prevent microbial growth and preserves the seed for future germination.
• Upon favorable conditions, seeds absorb water, kickstarting the germination process.

Proper storage of seeds at low moisture levels is crucial for their longevity and successful cultivation.

Corn Water Absorption

Corn plants are known for their significant water uptake, particularly as they reach maturity. Water is crucial for corn, especially in dry and hot conditions, to ensure optimal growth and yield.

Key points on water absorption in corn:

• A mature corn plant can absorb nearly three liters of water per day.
• Water helps in nutrient transport, photosynthesis, and maintaining structural integrity.
• Proper water management is critical for maximizing corn production, particularly during critical growth phases like tasseling and ear development.

Adequate irrigation and rainfall are essential to meet the high water demands of corn.

Mustard Water Absorption

Mustard plants are herbaceous and are known for their rapid growth and water absorption capabilities. This ability supports their fast life cycle and robust yield.

Details on mustard's water absorption:

• Mustard can absorb water equivalent to its own weight within about 5 hours.
• This rapid absorption ensures quick growth and development.
• It is critical to ensure that mustard crops receive adequate water, especially during the initial stages of growth.

The quick absorption rate helps mustard plants to thrive, making them resilient and well-adapted to various growing conditions.