examples21

id: 18937

lecture: A solution is made up of two or more substances that are completely mixed. In a solution, solute particles are mixed into a solvent. The solute cannot be separated from the solvent by a filter. For example, if you stir a spoonful of salt into a cup of water, the salt will mix into the water to make a saltwater solution. In this case, the salt is the solute. The water is the solvent. The concentration of a solute in a solution is a measure of the ratio of solute to solvent. Concentration can be described in terms of particles of solute per volume of solvent. concentration = particles of solute / volume of solvent

question: Which solution has a higher concentration of green particles?

choice: (A) Solution B (B) neither; their concentrations are the same (C) Solution A

context: The diagram below is a model of two solutions. Each green ball represents one particle of solute.

answer: A

Rationale:

0: A solution is made up of two or more substances that are completely mixed.
1: In a solution, solute particles are mixed into a solvent.
2: The solute cannot be separated from the solvent by a filter.
3: For example, if you stir a spoonful of salt into a cup of water, the salt will mix into the water to make a saltwater solution.
4: In this case, the salt is the solute.
5: The water is the solvent.
6: The concentration of a solute in a solution is a measure of the ratio of solute to solvent.
7: Concentration can be described in terms of particles of solute per volume of solvent.
8: concentration = particles of solute / volume of solvent In Solution A and Solution B, the green particles represent the solute.
9: To figure out which solution has a higher concentration of green particles, look at both the number of green particles and the volume of the solvent in each container.
10: Use the concentration formula to find the number of green particles per milliliter.
11: Solution A has more green particles per milliliter.
12: So, Solution A has a higher concentration of green particles.
13: The answer is C.

generated_skill:

solution: In Solution A and Solution B, the green particles represent the solute. To figure out which solution has a higher concentration of green particles, look at both the number of green particles and the volume of the solvent in each container. Use the concentration formula to find the number of green particles per milliliter. Solution B has more green particles per milliliter. So, Solution B has a higher concentration of green particles.

skill: Compare concentrations of solutions

id: 18994

lecture: Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes between magnets are called magnetic forces. The strength of a force is called its magnitude. The greater the magnitude of the magnetic force between two magnets, the more strongly the magnets attract or repel each other. You can change the magnitude of a magnetic force between two magnets by changing the distance between them. The magnitude of the magnetic force is smaller when there is a greater distance between the magnets.

question: Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

choice: (A) The magnitude of the magnetic force is the same in both pairs. (B) The magnitude of the magnetic force is smaller in Pair 2. (C) The magnitude of the magnetic force is smaller in Pair 1.

context: The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material, but some of them are different shapes.

answer: C

Rationale:

0: Magnets can pull or push on each other without touching.
1: When magnets attract, they pull together.
2: When magnets repel, they push apart.
3: These pulls and pushes between magnets are called magnetic forces.
4: The strength of a force is called its magnitude.
5: The greater the magnitude of the magnetic force between two magnets, the more strongly the magnets attract or repel each other.
6: You can change the magnitude of a magnetic force between two magnets by changing the distance between them.
7: The magnitude of the magnetic force is smaller when there is a greater distance between the magnets.
8: Distance affects the magnitude of the magnetic force.
9: When there is a greater distance between magnets, the magnitude of the magnetic force between them is smaller.
10: There is a greater distance between the magnets in Pair 2 than in Pair 1.
11: So, the magnitude of the magnetic force is smaller in Pair 2 than in Pair 1.
12: The answer is B.

generated_skill:

solution: Distance affects the magnitude of the magnetic force. When there is a greater distance between magnets, the magnitude of the magnetic force between them is smaller. There is a greater distance between the magnets in Pair 1 than in Pair 2. So, the magnitude of the magnetic force is smaller in Pair 1 than in Pair 2.

skill: Compare magnitudes of magnetic forces

id: 19112

lecture: A material is a type of matter. Wood, glass, metal, and plastic are common materials. Some objects are made of just one material. Most nails are made of metal. Other objects are made of more than one material. This hammer is made of metal and wood.

question: Which material is this clothes hanger made of?

choice: (A) cardboard (B) wood

context: N/A

answer: B

Rationale:

0: A material is a type of matter.
1: Wood, glass, metal, and plastic are common materials.
2: Some objects are made of just one material.
3: Most nails are made of metal.
4: Other objects are made of more than one material.
5: This hammer is made of metal and wood.
6: Look at the picture of the clothes hanger.
7: The clothes hanger is made of two different materials.
8: The top part is made of cardboard.
9: The rest of the hanger is made of metal.
10: Cardboard is a strong material.
11: But it is not as strong as metal.
12: So, the cardboard part of the hanger breaks easily.
13: The answer is A.

generated_skill:

solution: Look at the picture of the clothes hanger. The clothes hanger is made of two different materials. The hook is made of metal. The rest of the hanger is made of wood.

skill: Identify multiple materials in objects

id: 19197

lecture: A grid is made up of lines of squares. They are organized in rows and columns. A grid can help you use a map. A row is a line of squares that goes from side to side. Rows are marked with letters. A column is a line of squares that goes up and down. Columns are marked with numbers.

question: Which i in column 2?

choice: (A) the pond (B) the fast-food restaurant (C) the police department (D) the grocery store

context: N/A

answer: B

Rationale:

0: A grid is made up of lines of squares.
1: They are organized in rows and columns.
2: A grid can help you use a map.
3: A row is a line of squares that goes from side to side.
4: Rows are marked with letters.
5: A column is a line of squares that goes up and down.
6: Columns are marked with numbers.
7: The police department is in column 2.
8: The answer is C.

generated_skill:

solution: The fast-food restaurant is in column 2.

skill: Use a letter-number grid

id: 19227

lecture: Offspring phenotypes: dominant or recessive? How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype. If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait. If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait. A Punnett square shows what types of offspring a cross can produce. The expected ratio of offspring types compares how often the cross produces each type of offspring, on average. To write this ratio, count the number of boxes in the Punnett square representing each type. For example, consider the Punnett square below. | F | f F | FF | Ff f | Ff | ff There is 1 box with the genotype FF and 2 boxes with the genotype Ff. So, the expected ratio of offspring with the genotype FF to those with Ff is 1:2.

question: What is the expected ratio of offspring with white spots to offspring with solid coloring? Choose the most likely ratio.

choice: (A) 4:0 (B) 3:1 (C) 1:3 (D) 2:2 (E) 0:4

context: In a group of cows, some individuals have solid coloring and others have white spots. In this group, the gene for the coat pattern trait has two alleles. The allele for white spots (a) is recessive to the allele for solid coloring (A). This Punnett square shows a cross between two cows.

answer: E

Rationale:

0: Offspring phenotypes: dominant or recessive?
1: How do you determine an organism's phenotype for a trait?
2: Look at the combination of alleles in the organism's genotype for the gene that affects that trait.
3: Some alleles have types called dominant and recessive.
4: These two types can cause different versions of the trait to appear as the organism's phenotype.
5: If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
6: If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
7: A Punnett square shows what types of offspring a cross can produce.
8: The expected ratio of offspring types compares how often the cross produces each type of offspring, on average.
9: To write this ratio, count the number of boxes in the Punnett square representing each type.
10: For example, consider the Punnett square below.
11: | F | f F | FF | Ff f | Ff | ff There is 1 box with the genotype FF and 2 boxes with the genotype Ff.
12: So, the expected ratio of offspring with the genotype FF to those with Ff is 1:2.
13: To determine how many boxes in the Punnett square represent offspring with white spots or solid coloring, consider whether each phenotype is the dominant or recessive allele's version of the coat pattern trait.
14: The question tells you that the a allele, which is for white spots, is recessive to the A allele, which is for solid coloring.
15: White spots is the recessive allele's version of the coat pattern trait.
16: A cow with the recessive version of the coat pattern trait must have only recessive alleles for the coat pattern gene.
17: So, offspring with white spots must have the genotype aa.
18: All 4 boxes in the Punnett square have the genotype aa.
19: Solid coloring is the dominant allele's version of the coat pattern trait.
20: A cow with the dominant version of the coat pattern trait must have at least one dominant allele for the coat pattern gene.
21: So, offspring with solid coloring must have the genotype AA or Aa.
22: There are 0 boxes in the Punnett square with the genotype AA or Aa.
23: So, the expected ratio of offspring with white spots to offspring with solid coloring is 4:0.
24: This means that, based on the Punnett square, this cross will always produce offspring with white spots.
25: This cross is expected to never produce offspring with solid coloring.
26: The answer is A.

generated_skill:

solution: To determine how many boxes in the Punnett square represent offspring with white spots or solid coloring, consider whether each phenotype is the dominant or recessive allele's version of the coat pattern trait. The question tells you that the a allele, which is for white spots, is recessive to the A allele, which is for solid coloring. White spots is the recessive allele's version of the coat pattern trait. A cow with the recessive version of the coat pattern trait must have only recessive alleles for the coat pattern gene. So, offspring with white spots must have the genotype aa. There are 0 boxes in the Punnett square with the genotype aa. Solid coloring is the dominant allele's version of the coat pattern trait. A cow with the dominant version of the coat pattern trait must have at least one dominant allele for the coat pattern gene. So, offspring with solid coloring must have the genotype AA or Aa. All 4 boxes in the Punnett square have the genotype AA or Aa. So, the expected ratio of offspring with white spots to offspring with solid coloring is 0:4. This means that, based on the Punnett square, this cross will never produce offspring with white spots. Instead, this cross is expected to always produce offspring with solid coloring.

skill: Use Punnett squares to calculate ratios of offspring types

id: 19259

lecture: Magnets can pull or push on other magnets without touching them. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes are called magnetic forces. Magnetic forces are strongest at the magnets' poles, or ends. Every magnet has two poles: a north pole (N) and a south pole (S). Here are some examples of magnets. Their poles are shown in different colors and labeled. Whether a magnet attracts or repels other magnets depends on the positions of its poles. If opposite poles are closest to each other, the magnets attract. The magnets in the pair below attract. If the same, or like, poles are closest to each other, the magnets repel. The magnets in both pairs below repel.

question: Will these magnets attract or repel each other?

choice: (A) repel (B) attract

context: Two magnets are placed as shown.

answer: A

Rationale:

0: Magnets can pull or push on each other without touching.
1: When magnets attract, they pull together.
2: When magnets repel, they push apart.
3: Whether a magnet attracts or repels other magnets depends on the positions of its poles, or ends.
4: Every magnet has two poles: north and south.
5: Here are some examples of magnets.
6: The north pole of each magnet is labeled N, and the south pole is labeled S. If opposite poles are closest to each other, the magnets attract.
7: The magnets in the pair below attract.
8: If the same, or like, poles are closest to each other, the magnets repel.
9: The magnets in both pairs below repel.
10: To predict if these magnets will attract or repel, look at which poles are closest to each other.
11: The south pole of one magnet is closest to the north pole of the other magnet.
12: Opposite poles attract.
13: So, these magnets will attract each other.
14: The answer is B.

generated_skill:

solution: To predict if these magnets will attract or repel, look at which poles are closest to each other. The north pole of one magnet is closest to the north pole of the other magnet. Like poles repel. So, these magnets will repel each other.

skill: Identify magnets that attract or repel

id: 19367

lecture: When two organisms of different species interact in a way that affects one or both organisms, they form a symbiotic relationship. The word symbiosis comes from a Greek word that means living together. Scientists define types of symbiotic relationships based on how each organism is affected. This table lists three common types of symbiotic relationships. It shows how each organism is affected in each type of symbiotic relationship. Type of symbiotic relationship | Organism of one species... | Organism of the other species... Commensal | benefits | is not significantly affected Mutualistic | benefits | benefits Parasitic | benefits | is harmed (but not usually killed)

question: Which type of relationship is formed when an Alcon blue caterpillar lives in a Myrmica ant nest?

choice: (A) parasitic (B) mutualistic (C) commensal

context: Read the passage. Then answer the question. Alcon blue butterflies spend the first part of their lives as caterpillars that live with Myrmica ants. When a caterpillar lives with the ants, it mimics, or pretends to be, an ant. The caterpillar can mimic the ants by copying their smell. The caterpillar can also make noises that make it sound like a queen ant. Queen ants receive more food and better protection than any other ants in the nest. So, when the caterpillar mimics an ant, the ants feed and protect the caterpillar instead of other ants in the nest. Figure: a Myrmica ant caring for an Alcon blue caterpillar.

answer: A

Rationale:

0: When two organisms of different species interact in a way that affects one or both organisms, they form a symbiotic relationship.
1: The word symbiosis comes from a Greek word that means living together.
2: Scientists define types of symbiotic relationships based on how each organism is affected.
3: This table lists three common types of symbiotic relationships.
4: It shows how each organism is affected in each type of symbiotic relationship.
5: Type of symbiotic relationship | Organism of one species... | Organism of the other species... Commensal | benefits | is not significantly affected Mutualistic | benefits | benefits Parasitic | benefits | is harmed (but not usually killed) When an Alcon blue caterpillar lives in a Myrmica ant nest, the caterpillar gets food and protection.
6: So, the caterpillar benefits from its relationship with the ants.
7: The ants are not able to live as well as they did before the caterpillar moved in.
8: So, the ants are harmed by their relationship with the caterpillar.
9: Since the caterpillar benefits and the ants are harmed, a commensal relationship is formed when an Alcon blue caterpillar lives in a Myrmica ant nest.
10: The answer is C.

generated_skill:

solution: When an Alcon blue caterpillar lives in a Myrmica ant nest, the caterpillar gets food and protection. So, the caterpillar benefits from its relationship with the ants. The ants feed and protect the caterpillar instead of other ants in the nest. So, the ants are harmed by their relationship with the caterpillar. Since the caterpillar benefits and the ants are harmed, a parasitic relationship is formed when an Alcon blue caterpillar lives in a Myrmica ant nest.

skill: Classify symbiotic relationships

id: 19375

question: Which solution has a higher concentration of green particles?

choice: (A) Solution B (B) Solution A (C) neither; their concentrations are the same

context: The diagram below is a model of two solutions. Each green ball represents one particle of solute.

answer: A

Rationale:

0: A solution is made up of two or more substances that are completely mixed.
1: In a solution, solute particles are mixed into a solvent.
2: The solute cannot be separated from the solvent by a filter.
3: For example, if you stir a spoonful of salt into a cup of water, the salt will mix into the water to make a saltwater solution.
4: In this case, the salt is the solute.
5: The water is the solvent.
6: The concentration of a solute in a solution is a measure of the ratio of solute to solvent.
7: Concentration can be described in terms of particles of solute per volume of solvent.
8: concentration = particles of solute / volume of solvent In Solution A and Solution B, the green particles represent the solute.
9: To figure out which solution has a higher concentration of green particles, look at both the number of green particles and the volume of the solvent in each container.
10: Use the concentration formula to find the number of green particles per milliliter.
11: Solution A has more green particles per milliliter.
12: So, Solution A has a higher concentration of green particles.
13: The answer is B.

generated_skill:

skill: Compare concentrations of solutions

id: 19397

lecture: An adaptation is an inherited trait that helps an organism survive or reproduce. Adaptations can include both body parts and behaviors. The color, texture, and covering of an animal's skin are examples of adaptations. Animals' skins can be adapted in different ways. For example, skin with thick fur might help an animal stay warm. Skin with sharp spines might help an animal defend itself against predators.

question: Which animal is also adapted to be camouflaged in a sandy desert?

choice: (A) horned viper (B) European green lizard

context: s live in the deserts of southern Africa. The is adapted to be camouflaged in a sandy desert. Figure: Namaqua chameleon.

answer: A

Rationale:

0: An adaptation is an inherited trait that helps an organism survive or reproduce.
1: Adaptations can include both body parts and behaviors.
2: The color, texture, and covering of an animal's skin are examples of adaptations.
3: Animals' skins can be adapted in different ways.
4: For example, skin with thick fur might help an animal stay warm.
5: Skin with sharp spines might help an animal defend itself against predators.
6: Look at the picture of the Namaqua chameleon.
7: The Namaqua chameleon has sand-colored scales covering its body.
8: It is adapted to be camouflaged in a sandy desert.
9: The word camouflage means to blend in.
10: Now look at each animal.
11: Figure out which animal has a similar adaptation.
12: The European green lizard has green, brown, and yellow scales covering its body.
13: It is adapted to be camouflaged in a sandy desert.
14: The horned viper has a sand-colored body.
15: It is adapted to be camouflaged in a sandy desert.
16: The answer is B.

generated_skill:

solution: Look at the picture of the Namaqua chameleon. The Namaqua chameleon has sand-colored scales covering its body. It is adapted to be camouflaged in a sandy desert. The word camouflage means to blend in. Now look at each animal. Figure out which animal has a similar adaptation. The horned viper has sand-colored scales covering its body. It is adapted to be camouflaged in a sandy desert. The European green lizard has a green, brown, and yellow body. It is not adapted to be camouflaged in a sandy desert.

skill: Animal adaptations: skins and body coverings

id: 19470

question: Which solution has a higher concentration of blue particles?

choice: (A) neither; their concentrations are the same (B) Solution B (C) Solution A

context: The diagram below is a model of two solutions. Each blue ball represents one particle of solute.

answer: A

Rationale:

0: A solution is made up of two or more substances that are completely mixed.
1: In a solution, solute particles are mixed into a solvent.
2: The solute cannot be separated from the solvent by a filter.
3: For example, if you stir a spoonful of salt into a cup of water, the salt will mix into the water to make a saltwater solution.
4: In this case, the salt is the solute.
5: The water is the solvent.
6: The concentration of a solute in a solution is a measure of the ratio of solute to solvent.
7: Concentration can be described in terms of particles of solute per volume of solvent.
8: concentration = particles of solute / volume of solvent In Solution A and Solution B, the blue particles represent the solute.
9: To figure out which solution has a higher concentration of blue particles, look at both the number of blue particles and the volume of the solvent in each container.
10: Use the concentration formula to find the number of blue particles per milliliter.
11: Solution A has more blue particles per milliliter.
12: So, Solution A has a higher concentration of blue particles.
13: The answer is C.

generated_skill:

solution: In Solution A and Solution B, the blue particles represent the solute. To figure out which solution has a higher concentration of blue particles, look at both the number of blue particles and the volume of the solvent in each container. Use the concentration formula to find the number of blue particles per milliliter. Solution A and Solution B have the same number of blue particles per milliliter. So, their concentrations are the same.

skill: Compare concentrations of solutions