Which of the following statements are false ?
(I) Light is essential for life to exist on the earth.
(II) Many species of small plant under the canopy to tall trees in forest show optinal use of available light due to having large sized antenna molecules and higher number of thylakoids.
(III) UV-rays is not harmful for many organisms.
(IV) Photoperiodic requirement is not essential for many plants for flowering
(V) sun is the source of light and temperature for and .
(VI) Red algae can live in deeper water of sea because of having pigment phycoerythirn.

Options

A. only I
B. Only II
C. Only III
D. only IV & VI

Answer

To determine which statements are false, let's analyze each statement one by one:

1. **Statement I**: "Light is essential for life to exist on the earth."
- **Analysis**: This statement is true. Light, particularly sunlight, is crucial for photosynthesis, which is the foundation of most food chains on Earth.

2. **Statement II**: "Many species of small plants under the canopy of tall trees in forests show optimal use of available light due to having large-sized antenna molecules and a higher number of thylakoids."
- **Analysis**: This statement is also true. Plants that grow in low-light conditions, such as those under a canopy, have adapted to maximize light absorption through larger antenna molecules and more thylakoids.

3. **Statement III**: "UV-rays are not harmful for many organisms."
- **Analysis**: This statement is false. UV rays are indeed harmful to many organisms, including humans, as they can cause skin cancer and other health issues. The ozone layer protects us by filtering out most of the harmful UV radiation.

4. **Statement IV**: "Photoperiodic requirement is not essential for many plants for flowering."
- **Analysis**: This statement is true. While some plants require specific photoperiods (length of day and night) to flower, many others can flower without strict photoperiod requirements.

5. **Statement V**: "The sun is the source of light and temperature for Earth."
- **Analysis**: This statement is true. The sun provides the necessary light and warmth that sustain life on Earth.

6. **Statement VI**: "Red algae can live in deeper water of the sea because of having the pigment phycoerythrin."
- **Analysis**: This statement is true. Phycoerythrin allows red algae to absorb light at greater depths, enabling them to thrive in deeper waters.

**Conclusion**: The only false statement among the options provided is Statement III.

### Final Answer:
The false statement is: **III**.