Which of the following determines the strength of an acidic solution?
Litmus paper that turns red
Litmus paper that turns blue
Measured pH value equal to 7
Measured pH value less than 7
Correct Answer : D
Both litmus paper and a pH scale can be used to indicate whether a solution is acidic. However, a pH scale can also determine the strength of an acid.
Researchers can determine the strength of an acid or a base by measuring the pH of a solution. The pH value describes how acidic or basic a solution is. On pH scale, shown below, if the number is less than 7 the solution is acidic. A pH greater than 7 means the solution is basic. When the pH is exactly 7, the solution is neutral.
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Correct Answer is C
Explanation
One step of the scientific method is to analyze information or data collected from the experiment to conclude whether the hypothesis is supported.
Recall that these make up thescientific 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 anindependent variablethat the researcher modifies and adependent variablethat changes due to the independent variable. They also include acontrol groupused 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.
Correct Answer is A
Explanation
Correct Answer is D
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 eitherself-pollinateorcross-pollinate, when the pollen from one plant fertilizes the pistil of another plant. He also discovered that traits are eitherdominantorrecessive. 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 calledgenes.
- For each trait, an individual has two factors: one from each parent. If the two factors have the same information, the individual ishomozygousfor that trait. If the two factors are different, the individual isheterozygousfor that trait. Each copy of a factor, orgene, is called anallele.
- The alleles determine the physical appearance, orphenotype. The set of alleles an individual has is itsgenotype.
- An individual receives one allele from each parent.
- The presence of an allele does not guarantee that the trait will be expressed.
Correct Answer is B
Explanation
Mendel was accurately able to predict the patterns of heredity by studying rules related to genetics. These rules helped shape his theory of heredity. Heredity is the characteristics offspring inherit from their parents.
From experiments with garden peas, Mendel developed a simple set of rules that accurately predicted patterns of heredity. He discovered that plants eitherself-pollinateorcross-pollinate, when the pollen from one plant fertilizes the pistil of another plant. He also discovered that traits are eitherdominantorrecessive. 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 calledgenes.
- For each trait, an individual has two factors: one from each parent. If the two factors have the same information, the individual ishomozygousfor that trait. If the two factors are different, the individual isheterozygousfor that trait. Each copy of a factor, orgene, is called anallele.
- The alleles determine the physical appearance, orphenotype. The set of alleles an individual has is itsgenotype.
- An individual receives one allele from each parent.
- The presence of an allele does not guarantee that the trait will be expressed.
Correct Answer is C
Explanation
Homeostasisis the existence and maintenance of a relatively constant environment within the body. Each cell of the body is surrounded by a small amount of fluid, and the normal functions of each cell depend on the maintenance of its fluid environment within a narrow range of conditions, including temperature, volume, and chemical content. These conditions are known asvariables. For example, body temperature is a variable that can increase in a hot environment or decrease in a cold environment.
There are two types of feedback mechanisms in the human body: negative and positive.
- Negative Feedback: Most systems of the body are regulated by negative feedback mechanisms, which maintain homeostasis. Negative means that any deviation from the set point is made smaller or is resisted. The maintenance of normal blood pressure is a negative-feedback mechanism. Normal blood pressure is important because it is responsible for moving blood from the heart to tissues.
- Positive Feedback: Positive-feedback mechanisms are not homeostatic and are rare in healthy individuals. Positive means that when a deviation from a normal value occurs, the response of the system is to make the deviation even greater. Positive feedback therefore usually creates a cycle leading away from homeostasis and, in some cases, results in death. Inadequate delivery of blood to cardiac muscle is an example of positive feedback.
Correct Answer is B
Explanation
There are two major types of receptor molecules that respond to an intercellular chemical signal:
- Intracellular receptors: These receptors are located in either the cytoplasm or the nucleus of the cell. Signals diffuse across the cell membrane and bind to the receptor sites on intracellular receptors, of the same cell.
- Membrane-bound receptors: These receptors extend across the cell membrane, with their receptor sites on the outer surface of the cell membrane. They respond to intercellular chemical signals that are large, water-soluble molecules that do not diffuse across the cell membrane.
Correct Answer is B
Explanation
Pathogenis an infectious foreign body that enters the body and causes disease or illness to the person. There are five types of pathogens: viruses, bacteria, fungi, protozoa, and worms. Pathogens have antigen proteins found on their surface and are unique to each pathogen.
Antibodyis a protein produced by the body’s immune system when it detects harmful substances (antigens). There are many different antibodies found in the body. Each one is unique and protects the body against the specific antigen that it detects at any given time. If there are no antibodies for a specific antigen, the more likely you are to develop an illness.
Vaccinationsare the introduction of a dead or disabled pathogen or of a harmless microbe with the protein of a pathogen on its surface into the body. Often administered through needle injection, to stimulate the immune system to produce immunity to a specific disease Immunity protects the body from a disease when exposed to it.
There are four types of immunity: natural/passive, natural/active, artificial/passive, and artificial/ active.
- Natural/passive – Babies receive immunities from breastmilk.
- Natural/active – The body produces antibodies to combat an illness when a person becomes sick.
- Artificial/passive – This immunity is temporary and requires doses of serum to maintain the immunity.
- Artificial/active – A vaccination provides artificial/active immunity.
Correct Answer is D
Explanation
The autonomic nervous systemis responsible for activities that arenonvoluntaryand under unconscious control. This system controls glands and the smooth muscles of internal organs, heart rate, breathing, and digestion. The autonomic nervous system is further divided into the following:
- Sympathetic nervous system: The sympathetic nervous system focuses on emergency situations by preparing the body forfight or flight. (Sympathetic = Stress)
- Parasympathetic nervous system: The parasympathetic nervous system controls involuntary processes unrelated to emergencies. This system deals with “rest or digest” activities. (Parasympathetic = Peace)
Thesomatic nervous systemprimarily controlsvoluntaryactivities such as walking and riding a bicycle. Thus, this system sends information to the CNS and motor nerve fibers that are attached to skeletal muscle.
Correct Answer is D
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, acationforms. A cation is an ion with a net positive charge.
Correct Answer is A
Explanation
Only plant cells have cell walls, which help protect the cell and provide structural support. The cell wall also enforces the overall structural integrity of the plant cell, and it is found outside the cell membrane. The next organelle is a chloroplast. It is found in the cytoplasm of only plant cells.Chloroplastsare photosynthetic compounds usedto make food for plant cells by harnessing energy from the sun. These organelles play a role in photosynthesis.
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