6.1 Reproduction

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Question 39
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Table 1 gives the classification of four plant species.

Table 1

Classification GroupSpecies 1Species 2Species 3Species 4
KingdomPlantaePlantaePlantaePlantae
PhylumAngiospermsAngiospermsAngiospermsAngiosperms
ClassEudicotsEudicotsEudicotsEudicots
OrderBrassicalesFabalesBrassicalesFabales
FamilyBrassicaceaeFabaceaeBrassicaceaeFabaceae
GenusRaphanusPisumBrassicaVicia
Speciessativussativumnigrafaba
a.

Species 1 and 3 are the most closely related. What information in Table 1 gives evidence for this?

[1]
b.

Figure 1 shows the inheritance of certain characteristics in two species of plants.

Diagram showing two genetic crosses: The left side shows pea plants. The parental generation has a wrinkled seed crossed with a round seed, and their F1 offspring all have round seeds. It is noted that round shape (R) is dominant over wrinkled shape (r), and parents are homozygous. The right side shows radish plants. The parental generation has a long-rooted radish crossed with a round-rooted radish, and their F1 offspring all have oval roots. It is noted that long shape (S^L) and round shape (S^R) show incomplete dominance, and parents are homozygous.

  • In pea plants and in radish plants, the characteristic (seed shape or root shape) is controlled by one pair of alleles.
  • The parental generation plants are homozygous for these traits.
  • In heterozygous pea plants, the allele for round seed shape is dominant (RRR is the dominant round allele, rrr is the recessive wrinkled allele).
  • In heterozygous radish plants, the alleles for root shape are both expressed (SLS^LSL is the long-root allele, SRS^RSR is the round-root allele).

Use these symbols to answer the following questions:

What is the genotype of the round-seeded pea plants in the F1F_1F1​ generation?

[1]
c.

What is the genotype of a round-root radish plant?

[1]
d.

A grower crossed two oval-root radish plants. Write down the expected phenotypes of all possible offspring.

[2]
e.

What percentage of the offspring would we expect to have oval roots?

[1]

6.1 Reproduction Questions

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