Problem: Two frogs are being examined in a laboratory. Frog X was found in a pond in the forest and has a parasite in it. Frog Y was found just outside the laboratory and is missing one eye. The employees at the lab weren't planning on analyzing any frogs, but when they found the one outside their front door they changed their mind. Which frog is in a symbiotic relationship? Hint: They feed on living hosts. As parasites , fungi live in or on other organisms and get their nutrients from their host. Parasitic fungi use enzymes to break down living tissue, which may causes illness in the host. Disease-causing fungi are parasitic. Recall that parasitism is a type of symbiotic relationship between organisms of different species in which one, the parasite, benefits from a close association with the other, the host, which is harmed.

A: Frog X

Problem: Bill and Bob were two brothers. they were both into physical exercise, but Bill chose weight lifting, and Bob running. Which brother had fewer muscles contract against a resisting force? Hint: In exercises such as weight lifting, skeletal muscle contracts against a resisting force (see Figure below ). Using skeletal muscle in this way increases its size and strength. In exercises such as running, the cardiac muscle contracts faster and the heart pumps more blood. Using cardiac muscle in this way increases its strength and efficiency. Continued exercise is necessary to maintain bigger, stronger muscles. If you don't use a muscle, it will get smaller and weakerso use it or lose it.

A: Bob

Problem: A group of researches studied the green house gas emissions and their effects on Earth and people during the eighties compared to the twenties. During which decade did Earth experience an increased concentration of carbon dioxide? Hint: Current Situation : Currently the heating effect of extra greenhouse gases (since the start of the industrial revolution) is equal to about . Thus the recent period has recorded parallel increases in concentration of carbon dioxide and average global temperature. As more greenhouse gases are put into the atmosphere the temperature will increase further. There are certain effects of a warmer Earth (discussed more in optional section), which could accelerate the process, even if no more greenhouse gases are put into the atmosphere (an unlikely prospect for the foreseeable future).

A: eighties

Problem: Microbiologist John is studying the anaerobic organism. He collected two samples of this organism, sample A and sample B. Sample A is an anaerobic organism, and sample B is specifically identified as the Clostridium perfringens obligate anaerobe. To compare these samples to other organisms he collected another microbe that is not an anaerobic organism. He labeled it as sample C. Which sample would not use oxygen as terminal electron acceptor, sample A or sample C? Hint: An anaerobic organism is any organism that does not need oxygen for growth and even dies in its presence. Obligate anaerobes will die when exposed to atmospheric levels of oxygen. Clostridium perfringens bacteria, which are commonly found in soil around the world, are obligate anaerobes. Infection of a wound by C. perfringens bacteria causes the disease gas gangrene. Obligate anaerobes use molecules other than oxygen as terminal electron acceptors.

A:
sample A