What is the independent variable in the Daphnia heart rate experiment?

What is the independent variable in the Daphnia heart rate experiment?

The control is the heart rate of Daphnia prior to exposure to caffeinated solutions. The dependent variable is the heart rate measured before and after exposure. The independent variables are the seven caffeinated solutions that are tested on the Daphnia magna.

Which of these should be controlled variables throughout the Daphnia experiment?

What is being investigated in this lab experiment with respect to Daphnia? Which of these should be controlled variables throughout the Daphnia experiment? the amount of liquid present in the depression slide.

How is heart rate regulated in Daphnia?

The myogenic heart of the water flea Daphnia magna (D. magna) is regulated by inhibitory cholinergic neurons that modulate cardiac function, including heart rate.

What is the control in the Daphnia experiment?

In the case of our Daphnia, an example of a controlled variable would be the temperature of the water in which the Daphnia are tested. This variable needs to be controlled because Daphnia hearts beat faster in warm water than they do in cold water.

Does the size of Daphnia affect its heart rate?

Seventy-two Daphnia were used in the initial experiments. The average initial heart rate was 354 beats minute——1 (range: 91——521 beats minute——1). The large variation in heart rate between animals cannot be attributed to variation in their size.

What is the control variable in the Daphnia experiment?

Does caffeine affect heart rate Daphnia experiment?

Both caffeine and dopamine were found to instantly increase the heart rate of Daphnia in a dose-dependent manner. Interestingly, caffeine synergized with dopamine to increase Daphnia’s heart rate.

Why does Daphnia heart rate increase with temperature?

As body temperature increases, the rate of chemical reactions and physiological activities within the organism increase. The rate of cellular respiration increases, requiring more oxygen and producing more carbon dioxide. This requires an increased flow of blood, which is pumped by the heart.

Why does Daphnia heart rate increase?

Our data suggests that caffeine caused a significant increase in their heart rate (p=0.005024), and that ethanol caused a significant decrease in the heart rate of the Daphnia (p=0.028729). The results can be used to determine the effect ethanol and caffeine would have on humans.

Does caffeine affect heart rate of Daphnia?

How does sugar affect Daphnia heart rate?

The results of the experiment showed that high concentrations of sucrose, salt, and caffeine drastically increased the Daphnia’s heart rate. As the concentrations were diluted, the heart rate of the Daphnia decreased, reaching closer to the original heart rate.

How to make the most of the Daphnia heart rate lab?

Students commonly test the effects of chemical agents on the heart rate of the crustacean Daphnia magna, but the procedure has never been optimized. We determined the effects of three concentrations of ethanol, nicotine, and caffeine and of a control solution on heart rate in Daphnia.

How does ethanol affect heart rate in Daphnia?

We determined the effects of three concentrations of ethanol, nicotine, and caffeine and of a control solution on heart rate in Daphnia. Ethanol at 5%% and 10%% (v//v) reduced mean heart rate to ∼∼50%% and ∼∼20%% of its initial value, respectively. Recovery was rapid after removing 5%% ethanol, but recovery from 10%% ethanol took 20——30 minutes.

What are the control variables in the Daphnia experiment?

Control (independant) variables: • The volume of water given to daphnia under the microscope • The size of the daphnia • The same species of daphnia And there were more that were hard to control e. g the age of the daphnia as this was unknown.

Why are Daphnia so easy to care for?

Heart rates recover quickly after removing 5%% ethanol, which allows students to explore reversibility as an alternative to having a separate control group. Daphnia are small crustaceans that are inexpensive, easy to care for, and transparent. The latter property allows students to easily observe the beating heart ( Figure 1 ).