Question

A large number of roots from many genetically identical bean plants were cut into short pieces. The pieces were sorted into groups, depending upon their distance from the root tip. Some pieces from each group were used to find the mean dry mass of their cells. Thin sections cut from other pieces were examined with a light microscope to find the proportion of dividing cells and the mean volume of the cells. Suggest two variables, other than genotype, which need to be controlled to ensure similar root growth in different plants. In each case give the reason for your answer.

Answer 1

To ensure similar root growth in bean plants, control of soil composition and water availability is necessary. Consistent soil nutrients and pH, along with a regular watering schedule, help maintain uniform growth rates.

Step-by-step explanation:

When ensuring similar root growth in different bean plants, beyond genotype, several environmental and growth conditions need to be controlled. One such variable is soil composition and nutrients, which needs to be consistent across all plants. The nutrients available in the soil directly affect root development and growth rates. Essential nutrients like nitrogen, phosphorus, and potassium, along with the pH level and overall texture of the soil, should remain uniform to prevent variability in root growth.

Another variable is water availability. Water is crucial for plant growth and is involved in the transport of nutrients from the soil to the plant cells. Therefore, maintaining a consistent watering schedule and ensuring adequate soil moisture will help to make sure that root growth is not unduly influenced by variations in water stress or saturation.