1: Introducing Biology - Problems Flashcards
In the 19th century, childbed fever was common among women giving birth in hospital. It was believed that fear of hospitalisation caused the fatal disease. The death rates of childbed fever in Clinic I and Clinic II were 10% and 4% respectively.
It was observed that only doctors in Clinic I handled deliveries straight after dissecting dead bodies. The hypothesis was that doctors spread childbed fever from dead bodies to women. To test the hypothesis, doctors in Clinic I were requested to wash their hands before handling deliveries.
Suggest a suitable group for comparison of the results.
The death rate of childbed fever in a clinic with doctors who handle deliveries straight after dissection.
In the 19th century, childbed fever was common among women giving birth in hospital. It was believed that fear of hospitalisation caused the fatal disease. The death rates of childbed fever in Clinic I and Clinic II were 10% and 4% respectively.
It was observed that only doctors in Clinic I handled deliveries straight after dissecting dead bodies.
Is the hypothesis “fear of hospitalisation caused childbed fever” supported by the death rates? Explain.
No. The death rates of childbed fever were different in the two clinics. If fear of hospitalisation caused childbed fever, the death rates would have been similar in the two clinics.
In the 19th century, childbed fever was common among women giving birth in hospital. It was believed that fear of hospitalisation caused the fatal disease. The death rates of childbed fever in Clinic I and Clinic II were 10% and 4% respectively.
It was observed that only doctors in Clinic I handled deliveries straight after dissecting dead bodies. The hypothesis was that doctors spread childbed fever from dead bodies to women. To test the hypothesis, doctors in Clinic I were requested to wash their hands before handling deliveries.
State the expected result if the hypothesis is correct.
The death rate of childbed fever would be lower in the clinic in which doctors wash their hands before handling deliveries, compared to the clinic in which doctors handle deliveries right after dissection.
It was once believed that plants grew by absorbing materials from the soil. An experiment was designed to test the idea, in which a young tree was planted in a pot of dry soil, the pot was covered, and the tree was watered regularly for 5 years.
Experimental results: (initial mass, final mass) in kg
Tree (2.27, 76.74)
Dry soil (90.72, 90.66)
What is the purpose of covering the pot?
To prevent the exchange of any materials between the soil and the environment (such that the change in mass of the soil detected at the end of the experiment is attributed to the exchange of materials between the soil and the tree only).
It was once believed that plants grew by absorbing materials from the soil. An experiment was designed to test the idea, in which a young tree was planted in a pot of dry soil, the pot was covered, and the tree was watered regularly for 5 years.
State the hypothesis tested.
Plants grow by absorbing materials from the soil.
It was once believed that plants grew by absorbing materials from the soil. An experiment was designed to test the idea, in which a young tree was planted in a pot of dry soil, the pot was covered, and the tree was watered regularly for 5 years.
What is the expected result if the hypothesis tested is correct?
The increase in mass of the tree would be equal to the decrease in mass of the soil (such that the total mass of the tree and the soil is conserved).
It was once believed that plants grew by absorbing materials from the soil. An experiment was designed to test the idea, in which a young tree was planted in a pot of dry soil, the pot was covered, and the tree was watered regularly for 5 years.
Experimental results: (initial mass, final mass) in kg
Tree (2.27, 76.74)
Dry soil (90.72, 90.66)
Is the hypothesis tested supported or falsified by the result? Explain.
It is falsified, since the increase in mass of the tree is much greater than the decrease in mass of the soil (the total mass of the tree and the soil is not conserved; instead, it increased significantly during the course of the experiment).
