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Question:

Why are control groups used in experiments?

A To minimize the effect of variables
explanation

A control group is used to ensure that the number of variables that influences a data set is minimized. This is done by comparing measured data to the control group, which has many fixed variables.

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Related Questions

The addition of a catalyst to a chemical reaction will have what effect?

Increase the rate at which the reaction takes place.

A catalyst, by definition, is an enzyme that helps decrease the energy necessary to begin a reaction. Consequently, the addition of a catalyst to a chemical reaction will increase the rate at which the reaction takes place. A reduction in the energy required to begin the reaction means that the reaction will take place more quickly.

Which of the following descriptions is correct?

Gas: no definite volume and no definite shape

A gas is a substance with no definite volume and no definite shape. Solids and liquids have volumes that do not change easily.
A solid has a definite shape and volume. There are two kinds of solids—crystalline and amorphous.
Liquids can occupy whatever shape their container has, so they do not have a fixed shape. Because the particles in liquids are very close together (barely further apart than in solids) liquids do not easily compress, so their volume is fixed.

If you have 200 mL of a 60% sodium chloride solution, how much NaCl is dissolved in the solution?

120 g

A 60% NaCl solution would be made by dissolving 60 g of NaCl in slightly less than 100 mL of water, and then increasing the volume of the solution to the final 100mL of water. If we had 200 mL of a 60% NaCl solution, then there would be 120 g of NaCl dissolved in the solution.

Which of the following terms do these diagrams NOT portray?

Ion Channel

The first one is active transport as it requires ATP and the other two are symporter and antiporter respectfully. They both require facilitated transport. The only one not shown is an ion channel which requires no energy besides a gradient and is not active transport as it uses no ATP.

As air is inhaled, the sequence in which it passes through the respiratory tract is best described by which of the following choices?

Nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles

When inhaling, air is taken in through the mouth and nose, and then through the larynx and pharynx. These passageways warm the air and prepare it for gas exchange. The air continues on through the trachea, commonly referred to as the “windpipe”. The trachea then splits into a right and left bronchi, with each side dividing further into smaller bronchioles. While some bronchioles may directly be involved in gas exchange, the majority of them are part of the conducting airway, which simply moves air through the respiratory system to get them to the alveoli where most of the gas exchange occurs.

Which taxonomic rank is the next-smallest after Order?

Family

The taxonomy ranks run from largest to smallest: Kingdom, Phylum, Class, Order, Family, Genus, Species. The next-smallest after Order is Family. A useful mnemonic for remembering is, ‘King Philip Came Over For Great Spaghetti.’

Vibrio cholerae is a bacteria that causes the disease cholera. Disease-causing agents such as V. cholerae is referred to as a(n) ___________________.

Pathogen

Pathogens refer to agents, such as bacteria, viruses, and other microorganisms that cause diseases.
Interferons are signaling molecules released to elicit antiviral immune response.
A commensal microorganism refers to normal flora living in a host organism without causing harm or benefit.
A vaccine is a biological preparation that improves immunity against a particular disease.

Which of these is not a function of mitosis?

Producing gametes

Mitosis plays an important part in the life cycle of most living things, though to varying extents. In unicellular organisms such as bacteria, mitosis is a type of asexual reproduction, making identical copies of a single cell called daughter cells. In multicellular organisms, mitosis produces more cells for growth and repair.
Meiosis produces haploid gametes (ova or sperm) that contain one set of 23 chromosomes because they divide twice during the process.

What type of correlation is presented between price and quality?

weak direct correlation

Although the correlation is not strong, it appears that the price increases as the quality increases. This describes a weak direct correlation.

Dissolved oxygen (DO) is an important indicator of water quality, and oxygen levels that are too high or too low can harm aquatic ecosystems. A biologist noticed that fish were dying in a local lake and was concerned that the DO levels were too low to support aquatic life due to extremely high temperatures that summer. To measure the DO levels, she brought back several lake water samples to her laboratory to measure the DO concentration as a function of temperature. To do this, she heated several samples of lake water to various temperatures and then measured the DO concentration in each sample. Some samples were kept at the outdoors temperature. Which of the following is the independent variable?

Temperature

The independent variable is the variable that is controlled during an experiment to see how it influences the dependent variable. In this case, the temperature of the water was changed to see how it influenced the DO concentration.

Due to water’s polarity, water is known as which of the following?

universal solvent

Water is said to be polar, which means that there are opposite charges (+ and -) in the water molecule. This allows water to attract to other polar and ionic compounds and pull the compounds apart, therefore dissolving them. A solvent is a compound that is able to dissolve other compounds. A solute is the compound that gets dissolved. Water is not dissolved, but instead water is the compound that dissolves other compounds, therefore water is a solvent. As a note: water is unable to dissolve oils and fats because these compounds are non-polar and do not have charges that water can attract to and pull apart.[Earth and Physical Science]

A patient who has suffered head trauma is not able to recognize people he has met around an hour earlier but is still able to recognize people he met before the injury. He most likely has damage to the:

Hippocampus

The hippocampus is the site of memory storage. The medulla oblongata is involved in involuntary controls, the corpus callosum is involved in connections between the two lobes and in emotions and the Pituitary gland is an endocrine organ..

Which is NOT one of the four basic types of tissue?

parenchyma

The parenchyma of an organ consists of that tissue which conducts the specific function of the organ and comprises the bulk of the organ. It is not one of the four basic types of tissue: epithelial, nervous, connective, and muscle.

Cheetahs, rainbow trout, and inchworms belong to the same

Kingdom

All three animals belong to the same kingdom of Animalia, but are too different to be classed in the same phylum. Cheetahs and rainbow trout are in the Chordata phylum, while inchworms are in Arthropoda phylum.

Which of the following is a correct pairing of DNA bases?

A with T, C with G

This question refers to complementary bases - A always pairs with T and C always pairs with G.