An experiment on the effect of alcohol on the heart rate of Daphnia

An experiment on the effect of alcohol on the heart rate of DaphniaEffect of alcohol on the heart rate of Daphnia Alcohol with a volume fraction of 95% is commonly used in the experiment to prepare alcohol solutions of different concentrations Students are equipped with alcohol solutions with different concentration gradients as follows % etc. After a large number of experiments at about 15 room temperatures, adult Daphnia with a range of 30-36 times were selected as the material in the experiment.

1) Daphnia's heart rate in clear water is normal, put it in different concentrations of alcohol, the heart rate decreases, and the higher the alcohol concentration, the lower the Daphnia heart rate It means that the Daphnia heart rate is affected by alcohol, and the heart rate will decrease with the increase of alcohol concentration

2) As can be seen from the experiment record sheet, when the alcohol concentration reaches 20%, Daphnia will die due to excessive alcohol concentration

This is because alcohol has a paralyzing effect on the nervous system, so it slows down the beating of the heart

1) When the volume fraction of alcohol is ( clear water %, the corresponding Daphnia heart rate is (death) Indicates that the Daphnia heart rate will slow down with the increase of alcohol concentration Alcohol has the effect of anesthetizing the nervous system When the volume fraction of alcohol reaches 20%, Daphnia will stop beating (heart rate is 0) due to excessive alcohol concentration and complete anesthesia of the nervous system, causing death So according to the curve, the higher the alcohol concentration, the lower the heart rate of Daphnia (slower), It shows that alcohol has an inhibitory paralyzing effect on the heart rate of Daphnia (2) According to the data in **, the volume fraction of alcohol is ( clear water %, and the corresponding Daphnia heart rate is (death), so the curve chart in this experiment is changed to a histogram: (3) Through this experiment, we can realize that alcohol has an effect on the organism Alcoholism makes the central nervous system overexcited or paralyzed, and can also cause a variety of diseases of the cardiovascular system and digestive system, and if you drink too much alcohol at one time, it may also lead to death Therefore, excessive drinking will affect the health of the human body Teenagers should develop good living habits, do not drink, do not drink too much or advise relatives and friends not to drink alcohol, do not drink too much Therefore, the answer is: (1) The lower the heart rate (the slower) (2) (3) Alcohol abuse makes the central nervous system overexcited or paralyzed, and can also cause a variety of diseases of the cardiovascular system and digestive system, and if you drink too much alcohol at one time, it may also lead to death (the answer is reasonable).

An experiment on the effect of alcohol on the heart rate of DaphniaEffect of alcohol on the heart rate of Daphnia Alcohol with a volume fraction of 95% is commonly used in the experiment to prepare alcohol solutions of different concentrations Students are equipped with alcohol solutions with different concentration gradients as follows % etc. After a large number of experiments at about 15 room temperatures, adult Daphnia with a range of 30-36 times were selected as the material in the experiment.

1) Daphnia's heart rate in clear water is normal, put it in different concentrations of alcohol, the heart rate decreases, and the higher the alcohol concentration, the lower the Daphnia heart rate It means that the Daphnia heart rate is affected by alcohol, and the heart rate will decrease with the increase of alcohol concentration

2) As can be seen from the experiment record sheet, when the alcohol concentration reaches 20%, Daphnia will die due to excessive alcohol concentration

This is because alcohol has a paralyzing effect on the nervous system, so it slows down the beating of the heart

Objective: To understand the harm of alcohol to human health through the effect of alcohol on the heart rhythm of Daphnia.

Materials and utensils: microscopes, glass slides, straws, alcohol, graduated cylinders, timers, daphnia, etc.

Method step (1) Catch daphnia in the pond with a small net, or buy daphnia at the flower, bird, fish and insect market.

2) Pipette a Daphnia with a pipette and place it on the trapped glass slide, gently cover the coverslip, observe the Daphnia heart beating under the microscope and record the rate (times).

3) Add alcohol in different volume fractions to the slides dropwise.

4) Observe the effect of alcohol on the heart rhythm of Daphnia. Note: Daphnia have a fast heart rate and should be noted when counting.

There is a lack of specific experimental design and purpose for this question, so it is not possible to determine how many Daphnia are needed and how many groups they are divided into. But in general, when conducting experiments, the following factors need to be taken into account:

Purpose of the experiment: Clarify the purpose and research question of the experiment, and determine the experimental conditions and sample size required.

Control variables: During the experiment, it is necessary to control other factors that may affect the results of the experiment, such as temperature, light, etc. For different groups, it is necessary to maintain consistency of experimental conditions.

Sample size: Determine the number of samples that need to be grouped according to the purpose of the experiment and the research question. In general, the sample size should be large enough to guarantee the reliability and statistical significance of the experimental results.

Number of experimental groups and groups: The number of experimental groups and groups should be determined based on the experimental design and purpose. If it is necessary to compare the effects of different treatments, at least two experimental groups need to be established.

The number of samples in each experimental group should be the same to guarantee the comparability of experiments and the validity of statistical analysis.

In summary, more specific experimental design and purpose are needed to determine the number of Daphnia needed and the way in which they are grouped to collapse their panicles.

2) According to the hope of ** "Effect of alcohol on the heart rate of Daphnia", the question asked in the experiment is does alcohol have an effect on the heart rate of Daphnia? As can be seen from the figure, when the volume fraction of alcohol is ( clear water %, the corresponding Daphnia heart rate is ( Death) indicating that the Daphnia heart rate is easily affected by the alcohol concentration, that is, the Daphnia heart rate will decrease with the increase of alcohol concentration It can be hypothesized that alcohol solutions with different volume fractions have an effect on the Daphnia heart rate

3) The harmful components of alcohol will remain in the body of Daphnia during the experiment, affecting the heart rate of Daphnia and affecting the results of the experiment Therefore, only two experiments can be done with one Daphnia, and the heart rate of Daphnia must be counted in clear water first, and then the heart rate of Daphnia must be counted in a certain concentration of alcohol, and the order cannot be reversed

4) Analysis of the data in the table shows that the heart rate of Daphnia is easily affected by alcohol concentration, which decreases with the increase of alcohol concentration, and when the volume fraction of alcohol reaches 20%, Daphnia will cause cardiac arrest (heart rate is 0) due to excessive alcohol concentration, causing death It can be seen that alcohol has an effect on heart rate

Therefore, the answer is: 2) alcohol solutions with different volume fractions have an effect on the heart rate of Daphnia;

3) No; It will remain in the body of Daphnia and affect the results of the experiment;

4) Decreases as the alcohol concentration increases.