Analyzing the Passage and Blank 5

The passage describes the Sun's vital role in our Solar System and for life on Earth. It mentions that the Sun keeps our planet warm, provides light, and is the most important source of energy. The final sentence discusses what would happen if there were no Sun: "If there were no sun, many things wouldn't occur like photosynthesis or the presence of oxygen, which would have caused no (5) ______ of life."

We need to find the most appropriate word for blank 5 that fits the context of what the absence of the Sun, photosynthesis, and oxygen would cause in relation to life.

Evaluating Options for Blank 5

Let's look at the given options:

• skill: This refers to the ability to do something well. The lack of sun, photosynthesis, and oxygen would not prevent the development of skills; it would prevent life itself. So, this option doesn't fit.
• end: "End of life" means termination or death. However, the phrase is "no end of life". This usually means an abundance or continuous presence of life ("there is no end to the troubles"). If there were no sun, photosynthesis, and oxygen, there would definitely *not* be an abundance of life. This option is incorrect.
• enhancement: This means improvement or making something better. The absence of the sun wouldn't prevent the enhancement of existing life; it would prevent life from being there in the first place. So, this option is not suitable.
• existence: This refers to the state of being real or living. If there is "no existence of life", it means life would not exist. The passage states that without the sun, photosynthesis and oxygen wouldn't occur. These processes are fundamental for life on Earth. Therefore, their absence would indeed mean that life could not exist. This option fits the context perfectly.

Conclusion for Blank 5

Based on the analysis, the word that logically completes the sentence is "existence". The sentence "If there were no sun, many things wouldn't occur like photosynthesis or the presence of oxygen, which would have caused no existence of life" makes perfect sense, explaining that the absence of the Sun and its effects would prevent life from existing on Earth.

Revision Table: Key Concepts

Additional Information: Sun's Importance for Life

The passage highlights several critical roles the Sun plays in supporting life on Earth:

• Energy Source: The Sun is the primary energy source for almost all ecosystems on Earth. Plants use sunlight for photosynthesis, forming the base of most food chains.
• Temperature Regulation: The Sun warms the Earth, maintaining temperatures within a range suitable for liquid water and biological processes.
• Light: Sunlight is necessary for vision for many organisms and crucial for processes like photosynthesis.
• Photosynthesis and Oxygen: As mentioned, the Sun powers photosynthesis in plants and other organisms, which converts carbon dioxide and water into glucose (energy) and releases oxygen as a byproduct. Oxygen is then used by animals and other organisms for respiration. Without the Sun, this cycle would stop, depleting oxygen and energy sources necessary for life's existence.

Understanding these connections helps explain why the absence of the Sun would directly impact the very possibility of life existing.