examples0

id: 42

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 a woolly fleece to offspring with a hairy fleece? Choose the most likely ratio.

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

context: This passage describes the fleece type trait in sheep: The fleece, or outer coat, of a sheep is often cut off and used to make yarn for fabrics and other textiles. Woolly fleeces, which have shorter hairs, are usually used for clothing and blankets. Hairy fleeces, which have longer hairs, are usually used for carpets. In a group of sheep, some individuals have a hairy fleece and others have a woolly fleece. In this group, the gene for the fleece type trait has two alleles. The allele for a hairy fleece (F) is dominant over the allele for a woolly fleece (f). This Punnett square shows a cross between two sheep.

answer: B

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 a woolly fleece or a hairy fleece, consider whether each phenotype is the dominant or recessive allele's version of the fleece type trait.
14: The question tells you that the F allele, which is for a hairy fleece, is dominant over the f allele, which is for a woolly fleece.
15: A woolly fleece is the recessive allele's version of the fleece type trait.
16: A sheep with the recessive version of the fleece type trait must have only recessive alleles for the fleece type gene.
17: So, offspring with a woolly fleece must have the genotype ff.
18: There is 1 box in the Punnett square with the genotype ff.
19: This box is highlighted below.
20: A hairy fleece is the dominant allele's version of the fleece type trait.
21: A sheep with the dominant version of the fleece type trait must have at least one dominant allele for the fleece type gene.
22: So, offspring with a hairy fleece must have the genotype FF or Ff.
23: There are 3 boxes in the Punnett square with the genotype FF or Ff.
24: These boxes are highlighted below.
25: So, the expected ratio of offspring with a woolly fleece to offspring with a hairy fleece is 1:3.
26: This means that, on average, this cross will produce 1 offspring with a woolly fleece for every 3 offspring with a hairy fleece.
27: The answer is D.

generated_skill:

solution: To determine how many boxes in the Punnett square represent offspring with a woolly fleece or a hairy fleece, consider whether each phenotype is the dominant or recessive allele's version of the fleece type trait. The question tells you that the F allele, which is for a hairy fleece, is dominant over the f allele, which is for a woolly fleece. A woolly fleece is the recessive allele's version of the fleece type trait. A sheep with the recessive version of the fleece type trait must have only recessive alleles for the fleece type gene. So, offspring with a woolly fleece must have the genotype ff. All 4 boxes in the Punnett square have the genotype ff. A hairy fleece is the dominant allele's version of the fleece type trait. A sheep with the dominant version of the fleece type trait must have at least one dominant allele for the fleece type gene. So, offspring with a hairy fleece must have the genotype FF or Ff. There are 0 boxes in the Punnett square with the genotype FF or Ff. So, the expected ratio of offspring with a woolly fleece to offspring with a hairy fleece is 4:0. This means that, based on the Punnett square, this cross will always produce offspring with a woolly fleece. This cross is expected to never produce offspring with a hairy fleece.

skill: Use Punnett squares to calculate ratios of offspring types

id: 86

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 stronger the magnetic force between two magnets, the more strongly the magnets attract or repel each other. You can change the strength of a magnetic force between two magnets by changing the distance between them. The magnetic force is stronger when the magnets are closer together.

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

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

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.

answer: B

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 stronger the magnetic force between two magnets, the more strongly the magnets attract or repel each other.
5: You can change the strength of a magnetic force between two magnets by changing the distance between them.
6: The magnetic force is stronger when the magnets are closer together.
7: Distance affects the strength of the magnetic force.
8: When magnets are closer together, the magnetic force between them is stronger.
9: The magnets in Pair 2 are closer together than the magnets in Pair 1.
10: So, the magnetic force is stronger in Pair 2 than in Pair 1.
11: The answer is A.

generated_skill:

solution: Distance affects the strength of the magnetic force. When magnets are closer together, the magnetic force between them is stronger. The magnets in Pair 1 are closer together than the magnets in Pair 2. So, the magnetic force is stronger in Pair 1 than in Pair 2.

skill: Compare strengths of magnetic forces

id: 427

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

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

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.

answer: B

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 stronger the magnetic force between two magnets, the more strongly the magnets attract or repel each other.
5: You can change the strength of a magnetic force between two magnets by changing the distance between them.
6: The magnetic force is stronger when the magnets are closer together.
7: Distance affects the strength of the magnetic force.
8: When magnets are closer together, the magnetic force between them is stronger.
9: The magnets in Pair 1 are closer together than the magnets in Pair 2.
10: So, the magnetic force is stronger in Pair 1 than in Pair 2.
11: The answer is A.

generated_skill:

solution: Distance affects the strength of the magnetic force. When magnets are closer together, the magnetic force between them is stronger. The magnets in Pair 2 are closer together than the magnets in Pair 1. So, the magnetic force is stronger in Pair 2 than in Pair 1.

skill: Compare strengths of magnetic forces

id: 470

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: B

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 B has more green particles per milliliter.
12: So, Solution B has a higher concentration of green particles.
13: The answer is A.

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 A and Solution B have the same number of green particles per milliliter. So, their concentrations are the same.

skill: Compare concentrations of solutions

id: 600

lecture: Offspring genotypes: homozygous or heterozygous? How do you determine whether an organism is homozygous or heterozygous for a gene? Look at the alleles in the organism's genotype for that gene. An organism with two identical alleles for a gene is homozygous for that gene. If both alleles are dominant, the organism is homozygous dominant for the gene. If both alleles are recessive, the organism is homozygous recessive for the gene. An organism with two different alleles for a gene is heterozygous for that gene. In a Punnett square, each box represents a different outcome, or result. Each of the four outcomes is equally likely to happen. Each box represents one way the parents' alleles can combine to form an offspring's genotype. Because there are four boxes in the Punnett square, there are four possible outcomes. An event is a set of one or more outcomes. The probability of an event is a measure of how likely the event is to happen. This probability is a number between 0 and 1, and it can be written as a fraction: probability of an event = number of ways the event can happen / number of equally likely outcomes You can use a Punnett square to calculate the probability that a cross will produce certain offspring. For example, the Punnett square below has two boxes with the genotype Ff. It has one box with the genotype FF and one box with the genotype ff. This means there are two ways the parents' alleles can combine to form Ff. There is one way they can combine to form FF and one way they can combine to form ff. | F | f F | FF | Ff f | Ff | ff Consider an event in which this cross produces an offspring with the genotype ff. The probability of this event is given by the following fraction: number of ways the event can happen / number of equally likely outcomes = number of boxes with the genotype ff / total number of boxes = 1 / 4

question: What is the probability that an American curl cat produced by this cross will be homozygous dominant for the ear type gene?

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

context: In a group of American curl cats, some individuals have curled ears and others have straight ears. In this group, the gene for the ear type trait has two alleles. The allele for curled ears (E) is dominant over the allele for straight ears (e). This Punnett square shows a cross between two American curl cats.

answer: C

Rationale:

0: Offspring genotypes: homozygous or heterozygous?
1: How do you determine whether an organism is homozygous or heterozygous for a gene?
2: Look at the alleles in the organism's genotype for that gene.
3: An organism with two identical alleles for a gene is homozygous for that gene.
4: If both alleles are dominant, the organism is homozygous dominant for the gene.
5: If both alleles are recessive, the organism is homozygous recessive for the gene.
6: An organism with two different alleles for a gene is heterozygous for that gene.
7: In a Punnett square, each box represents a different outcome, or result.
8: Each of the four outcomes is equally likely to happen.
9: Each box represents one way the parents' alleles can combine to form an offspring's genotype.
10: Because there are four boxes in the Punnett square, there are four possible outcomes.
11: An event is a set of one or more outcomes.
12: The probability of an event is a measure of how likely the event is to happen.
13: This probability is a number between 0 and 1, and it can be written as a fraction: probability of an event = number of ways the event can happen / number of equally likely outcomes You can use a Punnett square to calculate the probability that a cross will produce certain offspring.
14: For example, the Punnett square below has two boxes with the genotype Ff.
15: It has one box with the genotype FF and one box with the genotype ff.
16: This means there are two ways the parents' alleles can combine to form Ff.
17: There is one way they can combine to form FF and one way they can combine to form ff.
18: | F | f F | FF | Ff f | Ff | ff Consider an event in which this cross produces an offspring with the genotype ff.
19: The probability of this event is given by the following fraction: number of ways the event can happen / number of equally likely outcomes = number of boxes with the genotype ff / total number of boxes = 1 / 4 The answer is A.

generated_skill:

solution:

skill: Use Punnett squares to calculate probabilities of offspring types

id: 734

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 a rat tapeworm attaches itself to a rat's intestine?

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

context: Read the passage. Then answer the question. A rat tapeworm is a type of flatworm that can live inside a rat's body. When a rat eats an insect that has a tapeworm inside it, the insect is digested, but the tapeworm remains alive. The tapeworm is moved into the rat's intestines and uses suckers to attach itself to the intestine wall. Inside the rat's intestine, the tapeworm absorbs nutrients from food that the rat has eaten. If the rat has many tapeworms in its intestines, it will become weak from lack of nutrients. Figure: a tapeworm attached to the wall of an intestine.

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 a tapeworm attaches itself to the wall of an intestine, the tapeworm gets nutrients that it needs to survive.
6: So, the tapeworm benefits from its relationship with the rat.
7: The rat is not helped by the tapeworm, but the rat is not harmed, either.
8: So, the rat is not significantly affected by its relationship with the tapeworm.
9: Since the tapeworm benefits and the rat is not significantly affected, a commensal relationship is formed when a rat tapeworm attaches itself to a rat's intestine.
10: The answer is C.

generated_skill:

solution: When a rat tapeworm attaches itself to a rat's intestine, the tapeworm gets nutrients that it needs to grow and survive. So, the tapeworm benefits from its relationship with the rat. The rat loses nutrients from its food to the tapeworm. So, the rat is harmed by its relationship with the tapeworm. Since the tapeworm benefits and the rat is harmed, a parasitic relationship is formed when a rat tapeworm attaches itself to the intestine of a rat.

skill: Classify symbiotic relationships

id: 752

lecture: A food web is a model. Models can make things in nature easier to understand. Models can be simpler than the things they represent. A food web is a model that shows where living things in an ecosystem get their food. If a food web showed every living thing in an ecosystem, the food web would be hard to understand. So, each food web shows how some living things in an ecosystem can get their food. Arrows show how matter moves. A food web has arrows that point from one living thing to another. Each arrow shows the direction that matter moves when one living thing eats another living thing. An arrow starts from the living thing that is eaten. The arrow points to the living thing that is doing the eating. A living thing in a food web can have more than one arrow pointing from it. This shows that the living thing is eaten by more than one other living thing in the food web. A living thing in a food web can also have more than one arrow pointing to it. This shows that the living thing eats more than one other living thing in the food web.

question: Based on the arrows, which of the following living things is a decomposer?

choice: (A) kelp (B) bat star

context: Below is a food web from an ocean ecosystem. The ecosystem is in Monterey Bay, off the coast of California. A food web is a model that shows how the matter eaten by living things moves through an ecosystem. The arrows show how matter moves through the food web.

answer: B

Rationale:

0: A food web is a model.
1: Models can make things in nature easier to understand.
2: Models can be simpler than the things they represent.
3: A food web is a model that shows where living things in an ecosystem get their food.
4: If a food web showed every living thing in an ecosystem, the food web would be hard to understand.
5: So, each food web shows how some living things in an ecosystem can get their food.
6: Arrows show how matter moves.
7: A food web has arrows that point from one living thing to another.
8: Each arrow shows the direction that matter moves when one living thing eats another living thing.
9: An arrow starts from the living thing that is eaten.
10: The arrow points to the living thing that is doing the eating.
11: A living thing in a food web can have more than one arrow pointing from it.
12: This shows that the living thing is eaten by more than one other living thing in the food web.
13: A living thing in a food web can also have more than one arrow pointing to it.
14: This shows that the living thing eats more than one other living thing in the food web.
15: Decomposers help break down dead living things into simpler matter, such as nutrients.
16: These nutrients can then help plants and other living things grow.
17: In a food web, there is an arrow pointing from another living thing to a decomposer.
18: There are no arrows pointing from a decomposer to another living thing.
19: The bat star has an arrow pointing from it.
20: So, the bat star is not a decomposer.
21: The kelp does not have arrows pointing from it to other living things.
22: So, the kelp is a decomposer.
23: The answer is A.

generated_skill:

solution: Decomposers help break down dead living things into simpler matter, such as nutrients. These nutrients can then help plants and other living things grow. In a food web, there is an arrow pointing from another living thing to a decomposer. There are no arrows pointing from a decomposer to another living thing. The kelp has an arrow pointing from it. So, the kelp is not a decomposer. The bat star does not have arrows pointing from it to other living things. So, the bat star is a decomposer.

skill: Interpret food webs

id: 841

lecture: A food web is a model. A food web shows where organisms in an ecosystem get their food. Models can make things in nature easier to understand because models can represent complex things in a simpler way. If a food web showed every organism in an ecosystem, the food web would be hard to understand. So, each food web shows how some organisms in an ecosystem can get their food. Arrows show how matter moves. A food web has arrows that point from one organism to another. Each arrow shows the direction that matter moves when one organism eats another organism. An arrow starts from the organism that is eaten. The arrow points to the organism that is doing the eating. An organism in a food web can have more than one arrow pointing from it. This shows that the organism is eaten by more than one other organism in the food web. An organism in a food web can also have more than one arrow pointing to it. This shows that the organism eats more than one other organism in the food web.

question: Which of these organisms contains matter that was once part of the lichen?

choice: (A) mushroom (B) short-tailed weasel (C) brown lemming (D) rough-legged hawk (E) bilberry

context: Below is a food web from a tundra ecosystem in Nunavut, a territory in Northern Canada. A food web models how the matter eaten by organisms moves through an ecosystem. The arrows in a food web represent how matter moves between organisms in an ecosystem.

answer: A

Rationale:

0: A food web is a model.
1: A food web shows where organisms in an ecosystem get their food.
2: Models can make things in nature easier to understand because models can represent complex things in a simpler way.
3: If a food web showed every organism in an ecosystem, the food web would be hard to understand.
4: So, each food web shows how some organisms in an ecosystem can get their food.
5: Arrows show how matter moves.
6: A food web has arrows that point from one organism to another.
7: Each arrow shows the direction that matter moves when one organism eats another organism.
8: An arrow starts from the organism that is eaten.
9: The arrow points to the organism that is doing the eating.
10: An organism in a food web can have more than one arrow pointing from it.
11: This shows that the organism is eaten by more than one other organism in the food web.
12: An organism in a food web can also have more than one arrow pointing to it.
13: This shows that the organism eats more than one other organism in the food web.
14: Use the arrows to follow how matter moves through this food web.
15: For each answer choice, try to find a path of arrows that starts from the lichen.
16: The only arrow pointing to the rough-legged hawk starts from the parasitic jaeger.
17: The only arrow pointing to the parasitic jaeger starts from the brown lemming.
18: The brown lemming has two arrows pointing to it.
19: These arrows start from the bear sedge and the bilberry.
20: Neither the bear sedge nor the bilberry has any arrows pointing to it.
21: So, in this food web, matter does not move from the lichen to the rough-legged hawk.There is one path matter can take from the lichen to the short-tailed weasel: lichen->barren-ground caribou->short-tailed weasel.
22: There are two paths matter can take from the lichen to the mushroom: lichen->barren-ground caribou->mushroom.
23: lichen->barren-ground caribou->grizzly bear->mushroom.
24: brown lemming.
25: The brown lemming has two arrows pointing to it.
26: These arrows start from the bear sedge and the bilberry.
27: Neither the bear sedge nor the bilberry has any arrows pointing to it.
28: So, in this food web, matter does not move from the lichen to the brown lemming.. bilberry.
29: The bilberry does not have any arrows pointing to it.
30: So, in this food web, matter does not move from the lichen to the bilberry..
31: The answer is E.

generated_skill:

solution: Use the arrows to follow how matter moves through this food web. For each answer choice, try to find a path of arrows that starts from the lichen. The bilberry does not have any arrows pointing to it. So, in this food web, matter does not move from the lichen to the bilberry.There are two paths matter can take from the lichen to the mushroom: lichen->barren-ground caribou->mushroom. lichen->barren-ground caribou->grizzly bear->mushroom. brown lemming. The brown lemming has two arrows pointing to it. These arrows start from the bear sedge and the bilberry. Neither the bear sedge nor the bilberry has any arrows pointing to it. So, in this food web, matter does not move from the lichen to the brown lemming.. short-tailed weasel. The only arrow pointing to the short-tailed weasel starts from the brown lemming. The brown lemming has two arrows pointing to it. These arrows start from the bear sedge and the bilberry. Neither the bear sedge nor the bilberry has any arrows pointing to it. So, in this food web, matter does not move from the lichen to the short-tailed weasel.. rough-legged hawk. The only arrow pointing to the rough-legged hawk starts from the parasitic jaeger. The only arrow pointing to the parasitic jaeger starts from the brown lemming. The brown lemming has two arrows pointing to it. These arrows start from the bear sedge and the bilberry. Neither the bear sedge nor the bilberry has any arrows pointing to it. So, in this food web, matter does not move from the lichen to the rough-legged hawk..

skill: Interpret food webs II

id: 843

lecture: Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. Whether a magnet attracts or repels other magnets depends on the positions of its poles, or ends. Every magnet has two poles, called north and south. Here are some examples of magnets. The north pole of each magnet is marked N, and the south pole is marked S. If different poles are closest to each other, the magnets attract. The magnets in the pair below attract. If the same 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) attract (B) repel

context: Two magnets are placed as shown. Hint: Magnets that attract pull together. Magnets that repel push apart.

answer: B

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, called north and south.
5: Here are some examples of magnets.
6: The north pole of each magnet is marked N, and the south pole is marked S. If different poles are closest to each other, the magnets attract.
7: The magnets in the pair below attract.
8: If the same poles are closest to each other, the magnets repel.
9: The magnets in both pairs below repel.
10: Will these magnets attract or repel?
11: To find out, look at which poles are closest to each other.
12: The north pole of one magnet is closest to the south pole of the other magnet.
13: Poles that are different attract.
14: So, these magnets will attract each other.
15: The answer is A.

generated_skill:

solution: Will these magnets attract or repel? To find out, 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. Poles that are the same repel. So, these magnets will repel each other.

skill: Identify magnets that attract or repel

id: 945

question: Based on the arrows, which of the following organisms is a consumer?

choice: (A) mushroom (B) lichen

answer: A

Rationale:

0: A food web is a model.
1: A food web shows where organisms in an ecosystem get their food.
2: Models can make things in nature easier to understand because models can represent complex things in a simpler way.
3: If a food web showed every organism in an ecosystem, the food web would be hard to understand.
4: So, each food web shows how some organisms in an ecosystem can get their food.
5: Arrows show how matter moves.
6: A food web has arrows that point from one organism to another.
7: Each arrow shows the direction that matter moves when one organism eats another organism.
8: An arrow starts from the organism that is eaten.
9: The arrow points to the organism that is doing the eating.
10: An organism in a food web can have more than one arrow pointing from it.
11: This shows that the organism is eaten by more than one other organism in the food web.
12: An organism in a food web can also have more than one arrow pointing to it.
13: This shows that the organism eats more than one other organism in the food web.
14: Consumers eat other organisms.
15: So, there are arrows in a food web that point from other organisms to consumers.
16: The lichen has arrows pointing to it from the barren-ground caribou and the collared lemming.
17: So, the lichen is a consumer.
18: The mushroom does not have any arrows pointing to it.
19: So, the mushroom is a producer, not a consumer.
20: The answer is B.

generated_skill:

solution: Consumers eat other organisms. So, there are arrows in a food web that point from other organisms to consumers. The mushroom has arrows pointing to it from the barren-ground caribou and the grizzly bear. So, the mushroom is a consumer. The lichen does not have any arrows pointing to it. So, the lichen is a producer, not a consumer.

skill: Interpret food webs