Can anyone help me with these Biology unit 3 questions?

Suggest why percentage of fish caught from sustainable sources are increasing?
How is deforestation causing change in the amount of different gases in the atmosphere?
Two things to consider when designing a artificial heart valve?
One disadvantage of having a large number of stomata per mm squared of leaf surface.
Why do fishes in a cage grow faster?
Explain how changes in the blood vessels supplying the skin caused the skin surface temperature to increase/decrease(not sure which one)
Why do potato peelings produce the most biogas

Reply 1

VioletPhillippo

I can help with some of these I think - I do triple science as well but we're only on the 2nd topic.
1. We are becoming more aware of sourcing fish ethically/more consumers want to buy it.
2. Deforestation- less oxygen released by photosynthesis of the trees
5. Fish in cages grow faster - fed nutrient rich food regularly, less room for movement
To be honest I think if you put them into Google you'd get some very good answers to most of them :smile:

Reply 2

chxnoa

1. Consumers are more aware of the benefits of buying sustainably sourced fish.
2. It is increasing the levels of carbon dioxide because of the slash-and-burn techniques used to clear forests (i.e.: plant matter is cut down and then burnt, and releases carbon dioxide as it is broken down by decay microbes or is burnt), and the loss of trees in general will increase carbon dioxide levels because they take in carbon dioxide during photosynthesis.
3. How long it will work for (really important!!), materials that it's made from (you don't want clots forming on the valve, because that could lead to strokes/heart attacks), perhaps cost.
4. The leaf will lose a lot of water in a short space of time.
5. The caged fish can't move as much as wild fish, so more of the energy they produce from respiration can go into growing and forming new tissues than in wild fish, which use a greater proportion of their energy for movement than caged fish do.
6. Skin surface temperature increases - blood vessels under the skin dilate, causing more heat to be lost by radiation from the skin surface. Skin surface temp. decreases - blood vessels under skin constrict, reducing blood flow to skin so that less heat is lost by radiation from skin surface.
7. ...not quite sure but they probably contain a lot of starch? So there is a lot of carbon/hydrogen already present to be broken down into biogas (which is methane, if I remember correctly).

Hope that helps c: