Amachine can never be 100% efficient because some work is always lost due to

Friction

Explanation:

The efficiency of a machine depends upon the percentage ratio of output work to the input work. More the difference between the input and output work, lesser will be the efficiency of the machine. In real machines, the output is always less than the input because a lot of work is consumed against friction, resulting in reduced output.

The formula for efficiency is:

Efficiency= ( Output work/Input work) x 100%

Since the output will always be lesser than the input, the ratio of output/input will always be lesser than 1 and, therefore, the efficiency will always be lesser than 100%

1. a host loses nutrients to a parasite

2. a parasite only benefits when the host is alive (cause if the host dies the parasite dies with it )

3. producers to consumers

4. the tapeworm is a parasite

5. they convert energy from the sun (photosynthesis)

6. sunflower-robin (i think im 80% sure)

7. producer

8. consumer

9. prey

10. fresh water snails ( cause the green algea is the producer and the snails are the primary consumers and the small fish consumer so is the big fish)