couple of questions regarding biology test

[serious7]

Hi, i'm a grade 10 high school student and i just had my biology test today. Basicly, i'm kind-of worried as the test was sortoff (bullshit) xD. Some of the questions wasn't even in our review so i'm deeply worried. I remmeber some of the multiple choice questions and i want to know your opinions as to what the answer may be.

 

1. Could the spring runoff off fertilizers that contain nitrogen and phosphorus be:

 

a)generally beneficial to the ecosystem

b)help grow excessive algae

 

I put answer A.

 

2. Which of the following biomes is best suitable to having trees losing leaves in the winter.

a) tundra

b)tropical rain forests

c)deciduous forest

d) all of the above

I put answer C.

[insane_alien]

number 1 should be b) but 2 is ok. (this is what i remember from the little biology i've took over the years. i'm sure a real biologist will be along to call us both idiots shortly.

[serious7]

BUT why is it be b?????? Isn't algae grown in the oceans? Fertilizers are used in soils by everyone so it is generally beneficial to ecosystems more than helping the growth of algae.

[insane_alien]

well, algae is found everywhere there is water, especially stagnant water like ponds and lakes. the fertilizers can lead to algae blooms that effectively extinguish all animal life in lakes and ponds. the chemicals aren't to nice for animals to ingest either.

[Mokele]

Isn't algae grown in the oceans? Fertilizers are used in soils by everyone so it is generally beneficial to ecosystems more than helping the growth of algae.

 

Algae grow anywhere and everywhere, fresh and salt water, lakes, streams, everwhere.

 

The problem is that dumping large amounts of nutrients into lakes via runoff leads to a huge increase in algae, which blocks out light to other water plants that fish and such eat. Then the algae die, and the decomposer bacteria use up all the oxygen, choking out the aquatic animals.

 

It's not a case of 'nutrients are bad' so much as 'dumping too much of *anything* all at once into a system leads to disturbance of the balance'.

 

Mokele