The question asks why fruits stored in a cold chamber have a longer storage life. This relates to the physiological processes occurring in fruits after harvest, particularly respiration, which leads to spoilage.
C) rate of respiration is decreased. Lowering the temperature in a cold chamber significantly reduces the metabolic rate of fruits, primarily by decreasing the rate of respiration. This slows down the consumption of stored food reserves and the processes of ripening and senescence, thereby extending their shelf life.
The question asks to identify which of the given phenomena are optical illusions. An optical illusion is a visually perceived image that differs from objective reality. We need to analyze each phenomenon based on the principles of light and perception.
Let's re-examine the options in light of common interpretations for competitive exams.
There seems to be a common misconception or a broader definition of "optical illusion" used in some contexts. Let's check the standard understanding for these phenomena.
However, some sources, especially in the context of general science, might loosely group phenomena caused by atmospheric optics (like scattering and refraction) under "optical phenomena" or even sometimes include them in a broader sense of "illusion" because they alter the appearance of celestial bodies. But strictly speaking, an optical illusion is a discrepancy between visual perception and physical reality due to the brain's interpretation, not a physical alteration of light before it reaches the eye.
Let's reconsider the options given the correct answer C (1, 2 and 4). This implies that "Colour of the sun at dawn" and "Twinkle of stars in the sky" are considered optical illusions in this context. This is a common point of confusion. While 1 is a true optical illusion, 2 and 4 are physical phenomena of atmospheric optics. However, in many competitive exams, atmospheric phenomena that alter the appearance of celestial bodies are often grouped under "optical illusions" or "optical phenomena" that create an altered perception.
Let's assume the broader interpretation where atmospheric effects leading to altered perception are included:
Based on this broader interpretation, 1, 2, and 4 would be considered optical illusions or related optical phenomena that cause an altered perception.
C) 1, 2 and 4
To understand the formation of a rainbow, we need to consider how sunlight interacts with individual raindrops. This involves several optical phenomena. We will analyze each phenomenon listed in the options to determine its role in rainbow formation.
All three phenomena—refraction, dispersion, and internal reflection—work together in sequence to produce the vivid colors and arc shape of a rainbow.
D) 1, 2 and 3 — All three physical phenomena (dispersion, refraction, and internal reflection) are essential for the formation of a rainbow. Sunlight first undergoes refraction and dispersion upon entering a raindrop, then total internal reflection inside the drop, and finally another refraction and dispersion upon exiting the drop, allowing us to see the spectrum of colors.
The question asks why transplanted seedlings often fail to grow. This requires understanding the critical components of a plant's root system and their function, especially during transplantation.
Correct Option: C) most of the root hairs are lost during transplantation. This is the most critical reason for the failure of transplanted seedlings. The delicate root hairs, which are primarily responsible for water and nutrient absorption, are easily damaged or detached during the transplantation process. Without these, the seedling cannot effectively take up resources from the new soil, leading to wilting and death.
The question asks to identify the symbiotic association that forms lichens, which are known for their ability to initiate ecological succession on bare rocks. This is a fundamental concept in biology and ecology.
Correct Option: B) algae and fungi
Lichens are a classic example of mutualism, where an alga (or cyanobacterium) and a fungus live together for mutual benefit. The alga performs photosynthesis, providing food, while the fungus provides a protective environment and absorbs water and minerals.
| Spacecraft | Purpose |
| 1) Cassini-Huygens | Orbiting the Venus and transmitting date to the Earth |
| 2) Messenger | Mapping and investigating the Mercury |
| 3) Voyager 1 and 2 | Exploring the outer solar system |
The question asks to identify the correctly matched pairs of spacecraft and their purposes. We need to evaluate each given pair based on general knowledge about space missions.
B) 2 and 3 only
Based on the evaluation, pairs 2 and 3 are correctly matched, while pair 1 is incorrect.