Why are flowers that bloom at night white or light in colour as compared to flowers. Class 9

Why are flowers that bloom at night white or light in colour as compared to flowers. Class 9

Question 1.

Why are flowers that bloom at night white or light in colour as compared to flowers that bloom during the day? Class 9

Answer:

Flowers that bloom at night are typically white or light in colour because they are pollinated by night-active (nocturnal) insects like moths. During the night, there is very little or no light, so bright colours would not be visible. However, white or light-coloured flowers reflect whatever little moonlight or starlight is available, making them more visible to nocturnal pollinators. Additionally, night-blooming flowers often produce strong fragrances to help attract pollinators in the dark when colour is less effective. During the day, flowers can use bright colours (red, yellow, orange, blue) to attract pollinators like bees, butterflies and birds, which have good colour vision.

Question 2.

Why do vegetatively propagated plants tend to be more vulnerable to diseases than sexually reproduced plants? Class 9

Answer:

Vegetatively propagated plants are genetically identical to the parent plant (clones). Since all individuals in the population have the same genetic makeup, if one plant is susceptible to a particular disease, pest or pathogen, all plants in the population will be equally susceptible. There is no genetic variation that might allow some individuals to be resistant. As a result, a single disease can wipe out an entire crop of vegetatively propagated plants.

In contrast, sexually reproduced plants have genetic variation due to the mixing of chromosomes from two parents during meiosis and fertilisation. This variation means that some individuals in the population may have genes that provide resistance to a particular disease, allowing the population to survive even if some individuals are affected. This makes sexually reproduced populations more resilient.