A very classic biology problem, if you can t figure it out, help

Eating chicken first and then corn can be seen according to the energy transfer of the biological chain.

Of course, we should eat wheat first, because the energy flow in the ecosystem is decreasing step by step, and the energy input to a nutrient concentration is not 100% into the next trophic level, and only 10% or 20% of the energy input to the next trophic level can flow into the next trophic level. You can think of it this way, if the energy transfer efficiency is 20% (which is the maximum), let's say the energy of the wheat is 100, and the energy of the chicken is 300, if we eat the chicken directly, we can get 60 energy, and then eat the wheat, we will get 20 energy, so that we will get a total of 80 energy: and if you eat the wheat first, the chicken will not feed it in order to maintain its energy, so that the energy of the wheat will flow to our level less than 20. This method obtains less than 80 percent of the energy

Now that you think about it, which way would you go for it? Hope it helps.

Plant the wheat, let the chickens and wheat be self-sufficient, and then you go fishing.

It is impossible for you to want to live for a long time in such a situation, you have no drinking water and no vitamins, and you will die of disease if you don't die of thirst.

Eat the chicken first, then the wheat. In this way, the energy you get is the energy of the chicken + the energy of the wheat; If you eat the wheat first, the chicken will have to consume the wheat, and you will get less energy; Of course, you can't let the chickens eat the wheat first, and then the eggs, because the conversion efficiency of energy flow from the first stage to the second stage is 10%-20%, and the energy obtained from eating eggs is much less than the energy of the wheat eaten by the chickens. So, if you eat chicken first, then wheat, the energy utilization rate is 100%.

Hehe, I know, dear.

Eat the chicken first, otherwise the chicken will eat the wheat, and then grow meat and poop. You can eat meat, but you can't eat poop. So you'd better eat the chicken first.

Question 1: a

After the hind toe is peeled, the sensation on the ** is damaged, and the most basic receptor of the solid reflex arc is gone, and the reflex arc cannot be generated.

Question 2: A can feel pain, which means that there is no problem with the receptors and afferent nerves, but the question obviously mentions that the lumbar spine is injured, causing leg movement disorders, so it is obviously not the effector that is the problem, then the answer must be the efferent nerve or nerve center!

When a student was doing an experiment on the digestion of starch by salivary amylase, the steps were as follows:

Inject 2 ml of 10% starch paste into one tube, add 2

Immediately after ml of saliva, drop the iodine solution, put the test tube into a water bath in warm water at 37 degrees Celsius for 10min, and then observe the phenomenon. The observation recorded by the student was that the starch paste did not change blue, and the experimental conclusion was that salivary amylase had a digestive effect on starch.

1) The student's shortcomings in experimental design are 1No controlled trials were done2The time for adding iodine solution in the experiment was not suitable.

2) The errors in the experimental protocol are ---1No controlled trials were done2The time for adding iodine solution in the experiment was not suitable.

3) The experimental phenomenon observed by the student should be --- turning blue.

4) Therefore, the conclusion reached by the student should be --- wrong.

(1) The student's shortcomings in experimental design are that there is no control ---.

2) The error in the experimental procedure is --- to add the enzyme solution first, then heat, then add reactants, and finally test and observe.

3) The experimental phenomenon observed by the student should be --- test tube A turns blue, and test tube B does not change blue.

4) Therefore, the student should conclude that --- salivary amylase has a digestive effect on starch.

P.S. The correct step is 1).

Inject 2 ml of saliva into one tube A

2) Inject 2 ml of distilled water into another tube

3) Put the test tube into a water bath in warm water at 37 degrees Celsius for 10min.

Inject 2 ml of 10% starch paste into both tubes.

5) Drop in iodine solution and observe the phenomenon.