Microscopic Life in Water

Question 1

What are the advantages of living in water?

Answer 1

• No risk of dehydration
• Temperature of water varies less than air
• Helps provide support
• Waste products easily disposed of

Question 2

What are the disadvantages of living in water?

Answer 2

• Water content of body can vary and needs to be controlled
• Denser than air so it has more resistance to movement
• Organisms in fresh water may take in too much water by osmosis and vice versa for salt water

Question 3

How are amoeba adapted to live in water?

Answer 3

They have a contracted vacuole that can store excess water which then fuses with the cell membrane and empties the water to the outside when it is full.

Question 4

What factors affect the photosynthesis of phytoplankton?

Answer 4

• Less light in winter and deeper in the water
• Temperature will be lower in winter and deep water
• Minerals are used up towards the end of summer

Question 5

What do marine food webs usually rely on as food sources?

Answer 5

• Green plants
• Deeper in ocean they rely on marine snow
• Can rely on bacteria deeper in the oceans to act as producers

Question 6

Why do chemicals such as PCBs and DDT kill animals at the top of the food chain?

Answer 6

• Toxic
• Don’t break down so they accumulate and become concentrated higher up the food chain (bioaccumulation)
• Affects animals with long lifespan