What standard is used to make comparisons in experiments?
A. Sample size
B. Control group
C. Dependent variable
D. Independent variable
A control group is a factor that does not change during an experiment. Due to this, it is used as a standard for comparison with variables that do change such as a dependent variable.
Recall that these make up the scientific method, described below:
- Problem: The question created because of an observation. Example: Does the size of a plastic object affect how fast it naturally degrades in a lake?
- Research: Reliable information available about what is observed. Example: Learn how plastics are made and understand the properties of a lake.
- Hypothesis: A predicted solution to the question or problem. Example: If the plastic material is small, then it will degrade faster than a large particle.
- Experiment: A series of tests used to evaluate the hypothesis. Experiments consist of an independent variable that the researcher modifies and a dependent variable that changes due to the independent variable. They also include a control group used as a standard to make comparisons.
- Example: Collect plastic particles both onshore and offshore of the lake over time. Determine the size of the particles and describe the lake conditions during this time period.
- Observe: Analyze data collected during an experiment to observe patterns.
- Example: Analyze the differences between the numbers of particles collected in terms of size.
- Conclusion: State whether the hypothesis is rejected or accepted and summarize all results.
- Communicate: Report findings so others can replicate and verify the results.
Therefore, the Correct Answer is B.
More Questions on TEAS 7 Science
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Q #1: A spoonful of sugar is added to a hot cup of tea. All the sugar dissolves. How can the resulting solution be described?
A. Saturated and homogeneous
B. Saturated and heterogeneous
C. Unsaturated and homogeneous
D. Unsaturated and heterogeneous
Answer Explanation
Because more solute could be added and dissolve, the solution has not yet reached its limit and is considered unsaturated. Because all the solute dissolves, the particles in the mixture are evenly distributed as a homogenous mixture.
- A mixture is when elements and compounds are physically, but not chemically, combined.
- A homogeneous mixture is when substances mix evenly and it is impossible to see individual components. A heterogeneous mixture is when the substances mix unevenly and it is possible to see individual components.
- A solution is a type of homogeneous mixture that is formed when a solute dissolves in a solvent.
- The concentration of a solution is the amount of a substance in a given amount of solution. An unsaturated solution has the ability to dissolve more solute and a saturated solution has already reached the limit of solute it can dissolve.
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Q #2: What phase is the cell cycle part of?
A. Interphase
B. Metaphase
C. Prophase
D. Telophase
Answer Explanation
Before mitosis or meiosis occurs, interphase must happen. This is when the cell cycle takes place. The cell cycle is an organized process divided into two phases: interphase and the M (mitotic) phase. During interphase, the cell grows and copies its DNA. After the cell reaches the M phase, division of the two new cells can occur. The G1, S, and G2 phases make up interphase.
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Q #3: Blood oxygen levels are most likely low when blood _____.
A. leaves the aorta
B. fills the right atrium
C. reaches body tissues
D. flows through arteries
Answer Explanation
Blood continually flows in one direction, beginning in the heart and proceeding to the arteries, arterioles, and capillaries. When blood reaches the capillaries, exchanges occur between blood and tissues. After this exchange happens, blood is collected into venules, which feed into veins and eventually flow back to the heart’s atrium. The heart must relax between two heartbeats for blood circulation to begin.
Two types of circulatory processes occur in the body:
Systemic circulation
- The pulmonary vein pushes oxygenated blood into the left atrium.
- As the atrium relaxes, oxygenated blood drains into the left ventricle through the mitral valve. 3. The left ventricle pumps oxygenated blood to the aorta.
- Blood travels through the arteries and arterioles before reaching the capillaries that surround the tissues.
Pulmonary circulation
- Two major veins, the Superior Vena Cava and the Inferior Vena Cava, brings deoxygenated blood from the upper and lower half of the body.
- Deoxygenated blood is pooled into the right atrium and then sent into the right ventricle through the tricuspid valve, which prevents blood from flowing backward.
- The right ventricle contracts, causing the blood to be pushed through the pulmonary valve into the pulmonary artery.
- Deoxygenated blood becomes oxygenated in the lungs.
- Oxygenated blood returns from the lungs to the left atrium through the pulmonary veins.
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Q #4: Which of the following atoms is a cation?
A. 14 protons, 14 neutrons, 18 electrons
B. 34 protons, 45 neutrons, 36 electrons
C. 35 protons, 44 neutrons, 35 electrons
D. 82 protons, 125 neutrons, 78 electrons
Answer Explanation
Because it has more protons than electrons, this atom has a positive charge and can be classified as a cation. When a metal such as sodium reacts to become stable, it loses its valence electrons. At first, it is a neutral atom with 11 protons and 11 electrons. When it loses an electron, the number of protons does not change, and the atom has 11 protons and 10 electrons. Because there is one more positively charged proton, a cation forms. A cation is an ion with a net positive charge.
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Q #5: After food has been masticated in the oral cavity, where does it go next?
A. Colon
B. Liver
C. Pancreas
D. Pharynx
Answer Explanation
Once the food has been masticated in the oral cavity (mouth), it is then swallowed and travels back into the pharynx down into the esophagus, which leads into the stomach.
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Q #6: During which of the following phase changes will the cohesion between the particles in a substance decrease?
A. Condensation
B. Deposition
C. Freezing
D. Vaporization
Answer Explanation
If the cohesion between particles decreases, then the particles must be undergoing a phase change that allows particles to move farther apart. This happens when a substance vaporizes and turns from liquid to gas. Any phase change that moves to the right in the diagram above requires energy to be added to the system because the substance has more energy at the end of the phase change. The phase changes are melting, vaporization (boiling), and sublimation. When energy is added, particles move faster and can break away from each other more easily as they move to a state of matter with a higher amount of energy. This is most commonly done by heating the substance.
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Q #7: Which statement best represents Mendel’s experiments with garden peas?
A. As a result, Mendel developed several theories that have since been disproved.
B. Mendel realized he was on an incorrect track, which led him to other experimental media
C. As a result, Mendel developed foundational conclusions that are still valued and followed today.
D. Mendel collaborated with others interested in genetics to develop heredity guidelines we still use today
Answer Explanation
Mendel developed theories of genetics that scientists around the world use today.
From experiments with garden peas, Mendel developed a simple set of rules that accurately predicted patterns of heredity. He discovered that plants either self-pollinate or cross-pollinate, when the pollen from one plant fertilizes the pistil of another plant. He also discovered that traits are either dominant or recessive. Dominant traits are expressed, and recessive traits are hidden.
Mendel’s Theory of Heredity
To explain his results, Mendel proposed a theory that has become the foundation of the science of genetics. The theory has five elements:
- Parents do not transmit traits directly to their offspring. Rather, they pass on units of information called genes.
- For each trait, an individual has two factors: one from each parent. If the two factors have the same information, the individual is homozygous for that trait. If the two factors are different, the individual is heterozygous for that trait. Each copy of a factor, or gene, is called an allele.
- The alleles determine the physical appearance, or phenotype. The set of alleles an individual has is its genotype.
- An individual receives one allele from each parent.
- The presence of an allele does not guarantee that the trait will be expressed.
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Q #8: What structure plays a role in air conduction?
A. Alveolus
B. Capillary
C. Lung
D. Trachea
Answer Explanation
The primary function of the respiratory system is to provide oxygen to and remove carbon dioxide from the body. In addition to gas exchange, the respiratory system enables a person to breathe. Breathing, or inhalation, is essential to life. It is the mechanism that provides oxygen to the body. Without oxygen, cells are unable to perform their functions necessary to keep the body alive. The primary muscle of inspiration is the diaphragm. Known as the chest cavity, this dome shaped structure flattens when it contracts. The rib cage moves outward, allowing outside air to be drawn into the lungs. During relaxation, the diaphragm returns to its dome shape and the rib cage moves back to its natural position. This causes the chest cavity to push air out of the lungs.
The respiratory system can be functionally divided into two parts:
- Air-conducting portion: Air is delivered to the lungs. This region consists of the upper and lower respiratory tract—specifically, the larynx, trachea, bronchi, and bronchioles.
- Gas exchange portion: Gas exchange takes place between the air and the blood. This portion includes the lungs, alveoli, and capillaries.
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Q #9: What type of bond forms between nitrogen and oxygen, and why?
A. Ionic, because electrons are shared
B. Covalent, because electrons are shared
C. Ionic, because electrons are transferred
D. Covalent, because electrons are transferred
Answer Explanation
Nitrogen and oxygen are both nonmetals, which means they will share electrons in a covalent bond. For example, two oxygen atoms form a double bond, in which two pairs of electrons (four electrons total) are shared. Similarly, two nitrogen atoms form a molecule with a triple bond, in which three pairs of electrons (six electrons total) are shared.
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Q #10: Which sequence describes the hierarchy level of biological organization?
A. Kingdom, phylum, class, order, family, genus, and species
B. Genus, class, kingdom, species, order, phylum, and family
C. Genus, class, kingdom, species, order, phylum, and family
D. Species, kingdom, genus, class, family, phylum, and order
Answer Explanation
Taxonomy is the process of classifying, describing, and naming organisms. There are seven levels in the Linnaean taxonomic system, starting with the broadest level, kingdom, and ending with the species level. For example, in the image the genus level contains two types of bears, but the species level shows one type. Additionally, organisms in each level are found in the level above it. For example, organisms in the order level are part of the class level. This classification system is based on physical similarities across living things. It does not account for molecular or genetic similarities.
