Traits controlled by many genes, and their bell-shaped spread
Grade 9 Science Worksheet - Challenge Me
Circle the best answer.
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Counts of 100 offspring in two model traits
class trait P trait Q 1 25 6 2 50 25 3 25 38 4 - 25 5 - 6 Jun compares two model traits that both peak in the middle. Which trait probably has more genes, and why?
- Neither, since both traits peak in the middle and have one gene
- Trait Q, since 38 is the largest count in the tables
- Trait P, since fewer and bigger steps point to more genes
- Trait Q, since 5 finer classes point to more genes
Classes in a model trait with additive alleles
classes dark alleles 9 0 to 8 Milo learns that a model trait has 9 classes, from 0 to 8 dark alleles. How many genes with two alleles each add up in this model?
- 5 genes, since half of 9 rounds up
- 8 genes, one gene for each dark allele
- 4 genes
- 9 genes, one gene for each class
Mean wheat plant height by seed lot and soil (model data)
seed lot poor soil (cm) rich soil (cm) lot P 90 110 lot Q 110 130 Zee compares lot P in poor soil with lot Q in rich soil, a gap of 40 cm. How is the gap shared between soil and seed lot?
- 30 cm from the soil and 10 cm from the seed lot
- 40 cm from the seed lot, since genes set height
- 40 cm from the soil, since it changed the alleles
- 20 cm from the soil and 20 cm from the seed lot
Mean barley plant height by seed lot and soil (model data)
seed lot poor soil (cm) rich soil (cm) lot R 60 85 lot S 80 ? Kira assumes rich soil adds the same height to each lot. What should the blank be for lot S in rich soil?
- 85 cm, the lot R value
- 130 cm, since the soil gain counts twice
- 80 cm, since soil does not matter
- 105 cm
Mean wheat plant height by seed lot and soil (model data)
seed lot poor soil (cm) rich soil (cm) lot P 90 110 lot Q 110 130 Ari plants seeds saved from lot P plants that grew in rich soil, and grows them in poor soil. What mean height does the table predict?
- About 70 cm, since poor soil lowers the lot a second time
- About 90 cm, the lot P poor-soil value
- About 100 cm, halfway between the two soils
- About 110 cm, since the seeds keep the soil's boost
Notebook for AaBb × AaBb (model data)
line what the notebook says 1 Each parent passes on one allele for each gene, chosen at random 2 The counts for 0, 1, 2, 3 and 4 dark alleles are 1, 4, 6, 4 and 1 3 These counts add to 15 offspring 4 The class with 2 dark alleles is the most common Noah's notebook is about one AaBb × AaBb cross. One line is wrong. Which fix is right?
- Line 4 should say the class with 2 dark alleles is the rarest
- Line 3 should say the counts add to 16 offspring
- Line 1 should say a parent passes on a blend of its two alleles
- Line 2 should have 3 classes, since one gene sets the trait
Notebook for one oat seed lot in two soils (model data)
line what the notebook says 1 One seed lot was grown in a poor soil and in a rich soil 2 The mean height was 100 cm in poor soil and 125 cm in rich soil 3 The 25 cm gap comes from the soil 4 So the rich soil changed the alleles in the seeds Pia's notebook is about one oat seed lot grown in two soils. One line is wrong. Which fix is right?
- Line 1 should say each soil had its own seed lot, since genes alone set height
- Line 2 should give a range, not a mean, for each soil
- Line 4 should say the soil changed how tall the plants grew, not the alleles
- Line 3 should say the gap is 225 cm, from adding the two means
Notebook for AaBbCc × AaBbCc (model data)
line what the notebook says 1 The model has 3 genes with additive alleles 2 That gives 0 to 6 dark alleles, so 6 classes 3 The counts are 1, 6, 15, 20, 15, 6 and 1 out of 64 4 More genes give a smoother bell shape Esme's notebook is about one AaBbCc × AaBbCc cross. One line is wrong. Which fix is right?
- Line 1 should say 6 genes, one for each dark allele
- Line 3 should read out of 7, the number of classes
- Line 2 should say 7 classes, since 0 to 6 is seven values
- Line 4 should say more genes give fewer classes
Ren reads a histogram of height for a whole model group. Which reply gives the best reason for the bell shape?
- Many genes set height by themselves, so surroundings play no part
- One gene sets height, so the group would split into two clear groups
- The bell shows the parents' heights blending into one middle height
- Many genes plus surroundings influence height, so a smooth bell is expected
Luz claims that a bell shape means offspring blend the parents' traits. Both parents here have 2 dark alleles. Which reply is best?
- No: 1 of 16 offspring has 0 dark alleles, fewer than either parent
- No: each class has the same count, so nothing could blend
- Yes: the most common class has 2 dark alleles, like the parents, so alleles blend
- No: the middle class is the rarest, so nothing could blend