Answer the following question given this paragraph: Some people have low levels of the neurotransmitter called serotonin in their brain. Scientists think that this is one cause of depression. Medications called antidepressants help bring serotonin levels back to normal. For many people with depression, antidepressants control the symptoms of their depression and help them lead happy, productive lives. Q: What according to scientists is the major cause of depression? Choices: - low thyroid levels - high fat diets - high serotonin levels - low serotonin levels A:
low serotonin levels

Answer the following question given this paragraph: Endocrine system: A high concentration of sugar in the blood triggers secretion of insulin by an endocrine gland called the pancreas. Insulin is a hormone that helps cells absorb sugar from the blood. Q: Which hormone helps cells absorb sugar from the blood? Choices: - estrogen - cortisol - adrenaline - insulin A:
insulin

Answer the following question given this paragraph: Steels are a very important class of alloys. The many types of steels are primarily composed of iron, with various amounts of the elements carbon, chromium, manganese, nickel, molybdenum, and boron. Steels are widely used in building construction because of their strength, hardness, and resistance to corrosion. Most large modern structures like skyscrapers and stadiums are supported by a steel skeleton (see Figure below ). Q: What is the primary component of steel alloys? Choices: - carbon - titanium - alluminum - iron A:
iron

Answer the following question given this paragraph: We obviously can't live without plants, but sometimes they cause us problems. Many plants are weeds. Weeds are plants that grow where people don't want them, such as gardens and lawns. They take up space and use resources, hindering the growth of more desirable plants. People often introduce plants to new habitats where they lack natural predators and parasites. The introduced plants may spread rapidly and drive out native plants. Many plants produce pollen , which can cause allergies. Plants may also produce toxins that harm human health (see Figure below ). Q: What are plants called that grow where you don't want them? Choices: - grasses - shrubs - reeds - weeds A:
weeds