Numerical Problems/ISC/Class 11
Created by Titas Mallick
Biology Teacher • M.Sc. Botany • B.Ed. • CTET (CBSE) • CISCE Examiner
Created by Titas Mallick
Biology Teacher • M.Sc. Botany • B.Ed. • CTET (CBSE) • CISCE Examiner
Numerical Problems - Plant Growth and Development
A plant stem initially measures 5 cm in length. After 10 days, its length increases to 15 cm. Assuming arithmetic growth, calculate the growth rate per day.
Solution:
Arithmetic growth is characterized by a constant increase in length over time. The formula for arithmetic growth rate is:
Growth Rate = (Final Length - Initial Length) / Time
Given:
Growth Rate = (15 cm - 5 cm) / 10 days Growth Rate = 10 cm / 10 days Growth Rate = 1 cm/day
Therefore, the plant stem's arithmetic growth rate is 1 cm per day.
Plant A increases its leaf area from 10 cm² to 20 cm² in a week. Plant B increases its leaf area from 100 cm² to 110 cm² in the same week. Which plant shows a higher relative growth rate?
Solution:
Relative growth rate (RGR) is the growth per unit of initial size over a given period. It is a more accurate measure for comparing growth in organisms of different initial sizes.
Plant A: Increase in area = 20 cm² - 10 cm² = 10 cm² Relative growth rate = (Increase in area / Initial area) = 10 cm² / 10 cm² = 1 (or 100% increase)
Plant B: Increase in area = 110 cm² - 100 cm² = 10 cm² Relative growth rate = (Increase in area / Initial area) = 10 cm² / 100 cm² = 0.1 (or 10% increase)
Although both plants increased their leaf area by the same absolute amount (10 cm²), Plant A shows a higher relative growth rate because its growth is a larger proportion of its initial size.
Therefore, Plant A shows a higher relative growth rate.
/Numerical-Problems/ISC/Class-11/Class_XI_Biology_Chapter_Plant_Growth_and_Development_Topic_Growth_Rate_Numerical_Problems.mdx