Questions: Why is grafting sometimes used in asexual reproduction of plants? to make sure that the plant is not an exact genetic copy of the parent plant to make it harder to grow a new plant to make it take a lot longer and become more expensive to combine the desirable characteristics of two or more plants

The answer is the fourth one: to combine the desirable characteristics of two or more plants.

Explanation for each option:

1. To make sure that the plant is not an exact genetic copy of the parent plant: This is incorrect. Grafting is used to propagate plants asexually, which typically results in offspring that are genetically identical to the parent plant. The purpose is not to create genetic variation but to maintain specific desirable traits.

2. To make it harder to grow a new plant: This is incorrect. Grafting is not intended to make plant propagation more difficult. In fact, it is used to facilitate the growth of plants with specific characteristics that might be difficult to achieve through other methods.

3. To make it take a lot longer and become more expensive: This is incorrect. While grafting can be more labor-intensive and costly than other methods, the goal is not to increase time or expense. The benefits of combining desirable traits often outweigh these factors.

4. To combine the desirable characteristics of two or more plants: This is correct. Grafting allows the combination of desirable traits from different plants, such as disease resistance from one plant and fruit quality from another, resulting in a plant that has the best characteristics of both.

In summary, grafting is used in asexual reproduction of plants to combine the desirable characteristics of two or more plants, making it a valuable technique in horticulture and agriculture.