The little woman is super kneeling and begging for the answer to the biology question in the first y

This is the same as why people generally only give birth to one litter at a time, fertilization in the body, high sperm-egg binding rate, and high survival rate of babies.

And fish fertilization in vitro has a low binding rate and a low survival rate of fish.

To put it in layman's terms, it means that if you are more productive, you will live a little more, and you will be prepared and free from trouble.

From the analysis of the hatching rate of fish eggs and bird eggs and the survival rate of offspring, the hatching rate and survival rate of fish eggs are much lower than that of bird eggs, and if there are as few as bird eggs, they will soon become extinct, but fish has its own way of continuing the race, that is, a large number of eggs, even if many are eaten or cannot survive, but it can also ensure the continuation of its race.

- Dividing line ---

The more eggs they lay in the animals, the more careless they are in the care of their offspring, so the mortality rate is high, and the large number of eggs laid can ensure that some will always survive; Animals that lay fewer eggs are more dedicated to the care of their offspring, and the mortality rate of their offspring is lower, so it is not necessary to lay a lot of eggs.

Two meanings in one.

Of course, because fish and birds live in different environments, and fish have a relatively harsher environment, so they must lay more eggs to adapt to the environment. Otherwise, if the fish had laid as few eggs as birds, they would have gone extinct long ago!

(1) The balls must be placed in a place where there is sunlight, because sunlight provides power to maintain the energy flow and material circulation of the ecosystem.

2) The energy flow in this ball is: sunlight, algae, and small fish.

3) The reason why small fish and algae can survive is that algae provide O2 and nutrients for small fish through photosynthesis, small fish provide CO2 for photosynthesis of algae through respiration, and the excrement is decomposed into simple small molecule substances by decomposers and then used by algae.

There are sunshine algae - small fish.

Small fish provide carbon dioxide and excrement as nutrients for the growth of algae, and algae provide oxygen and food for small fish.

Sunny place.

Sunlight --- algae (photosynthesis - production of oxygen, food for small fish) - small fish (digestion).

There is a relatively complete biological chain.

Sunlight in the sun, algae and small fish.

Interdependence.

1.If all kinds of bacteria and fungi in nature cease to exist, then the following statement is incorrect (a).

a.Biology questions are highly perishable. Because there are no bacteria and fungi of all kinds.

2.On cucumber plants, most of the flowers do not bear fruit. The reason is (a).

This question is actually very simple, first of all, it is to increase the yield, and the d you choose is to reduce the oxygen content will directly lead to a reduction in yield, which may lead to the death of the plant, because the plant has a respiration effect, it also needs oxygen, especially at night, when there is no light, the demand for oxygen will increase, because there is no photosynthesis, so it can not produce oxygen by itself, and it can only be ingested from the outside world, and if the oxygen content is reduced, it is like a person suffocating, how can it be possible to increase the yield? A has nothing to do with this question, B is the same reason, it should be an increase, not a decrease, so choose C. The respiration of plants is particularly active at a certain temperature, and if we want to increase the yield, we need to reduce the consumption of the plant itself, so appropriately reducing the temperature can reduce the consumption, so as to achieve the purpose of increasing the yield.

Lowering the night temperature inhibits the respiration of vegetables at night, reduces the metabolism of sugars in the plant, and increases the average daily accumulation of organic matter, which also improves the yield of vegetables!

The high oxygen content makes the respiration more sufficient, and the belt also needs to have a certain temperature.

The reason for reducing the nighttime temperature is to make the temperature difference between day and night large, which is conducive to the accumulation of nutrients for vegetables.

As for reducing the oxygen content, dear, plants do not photosynthesize at night, at night they inhale oxygen and exhale carbon dioxide, you reduce the amount of oxygen, let alone increase the yield and whether you can survive is a problem.