Students know that earth climate has changed over time. The evidence includes the study of three rings, ice cores, ocean sediments, and glacier lengths. Evidence indicates that earth is presently becoming warmer. Some scientist conclude that global warming is from human activities, and other scientist conclude that the warming is a result of the earths natural cycles. Which concept is best illustrated

Only an electron microscope can be used to view

A scientist is developing a system to remove harmful bacteria from a contaminated water supply. In order to trap the bacteria and prevent them from going through the filter, she must make sure the pores in the filter are no larger than

A controlled experiment is one that

Which of the following statements is an example of qualitative data?

The graph below shows a typical growth curve. What is happening at Point 3 in the graph?

Scientists conducted a study to determine the optimal amount of folic acid needed in the mothers diet to prevent neural tube defects. The results are shown in the graph below. According to the graph, what is the minimum amount of folate needed to reduce the risk of neural tube defects to 10 or less per 10,000 births?

A pharmaceutical company developed a new drug (drug A) to replace an existing drug (drug B) that had been used in treating a disease for 25 years. The hypothesis was that patients would have fewer side effects from drug A than from drug B. The company appointed an independent coordinator to select a group of people with the disease for testing. The coordinator randomly divided the people into two equal groups. One group received drug A, and the other group received drug B. At the end of the study, the coordinator revealed to the company researchers that drug A treated the disease as well as drug B, and patients had fewer side effects. Why is the conclusion from this study free of bias?

Researchers studied populations of Ixodes ricinnus nymphs in Sweden at three different sites over a five-year period. Site 1 was a temporary stream, Site 2 was a permanent stream, and Site 3 was a lake. They collected samples on the first day of the year with a temperature of 20 degrees Celsius and recorded the ratio of females to males captured. Figure 1 shows the resulting data. * Which of the following factors were kept constant in the experiment?

Students did an experiment to determine if a substance contained glucose. To determine if glucose was present, they added 5 mL of Benedict's solution to a test tube of corn syrup and then heated the mixture. A change to a brick red color was a positive indicator for glucose. Which piece of equipment provides the most precise measurement of the volume of Benedict's solution?

The graph below shows the food intake of various species of grazing animals. Which statement correctly describes the feeding pattern of one of these animals?

Students are studying the effect of fertilizer on plant growth. The students * will measure 75 milliliters (mL) of water and 5 milliliters (mL) of liquid fertilizer and mix the two together before adding the mixture to plants. Which piece of equipment would be most accurate for measuring the water that the students will need?

A student is comparing hundreds of leaves of the same tree species. The * student will calculate each leaf area using a formula. The formula requires the measurements of length and width of each leaf. When all the data are collected, the student will display differences of leaves from individual trees on a graph. Which of these tools will the student use to gather and display the data in this investigation?

Noroviruses are a group of viruses that cause gastroenteritis (stomach inflammation) in people. Like all viral infections, noroviruses are not affected by treatment with antibiotics. Although viruses can cause illness in humans, similar to bacterial infection the main argument supporting the idea that viruses are not alive is

A Basilisk lizard like the one shown is a reptile. Reptiles often modify their behavior in order to help control body temperature. When their body temperature is low, reptiles often bask in the sun. When their body temperature is too high, they will often hide in shady and cool places. When reptiles alter their behavior in order to help control their body temperature, what characteristic of living organisms is being shown?

In a biology lab, students did an experiment to study how the mass of a piece of potato in the shape of a cube changed. They determined the mass of the cube, placed the cube in a 10% salt solution, and measured the mass of the cube again. Which piece of equipment did the students use to measure the mass of the potato cube?

Why do viruses need living hosts, such as bacteria or eukaryote cells?

The graph below shows the acid tolerance of nine species living in water at * different pH values. Which statement best represents the information shown in the graph?

The process by which an organism's internal environment is kept stable in spite of changes in the external environment is called