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Date	May 2019	Marks available	2	Reference code	19M.2.SL.TZ2.4
Level	Standard level	Paper	Paper 2	Time zone	Time zone 2
Command term	Explain	Question number	4	Adapted from	N/A

Question

The images show parts of plants belonging to two different phyla.

State the phylum of plant X and of plant Y.

[2]

Explain one cause of mutation.

[2]

Outline the types of evidence that can be used to place a species in a particular clade.

[3]

The cladogram includes four marsupial (non-placental mammal) families.

[Source: Koala image: Quartl, https://commons.wikimedia.org/wiki/Phascolarctos_cinereus#/media/
File:Friendly_Female_Koala.JPG; Wombat image: JJ Harrison, https://en.wikipedia.org/wiki/Wombat#/
media/File:Vombatus_ursinus_-Maria_Island_National_Park.jpg; Marsupial lion: Nobu Tamura,
https://en.wikipedia.org/wiki/Marsupial_lion#/media/File:Thylacoleo_BW.jpg;
Diprotodontoidea image: Anne Musser]

Deduce the family that is most closely related to the Diprotodontoidea.

[1]

Markscheme

X: Filicinophyta ✔

Y: Coniferophyta/Conifera/Gymnosperms ✔

Not chromosomal.

a. a clade is a group of organisms that have evolved from a common ancestor ✔

b. identify the base sequences of a gene ✔

c. identify amino acid sequence of a protein ✔

d. comparing homologous structures ✔

e. the fewer the differences, the closer they diverged in time from a common ancestor ✔ Accept vice versa.

Vombatidae/wombats ✔

Examiners report

Those who had been taught it could identify the filicinophyte and the coniferophyte, albeit with a variety of spellings.

Many were confused by a relatively simple question, but a large proportion gained both marks by linking radiation or carcinogens to changes in the DNA base sequence.

Those who had been taught it gained at least two marks for evidence and clades, with comparing base sequences of genes and amino acid sequences of proteins amongst the most common correct answers.

Nearly everyone spotted the wombat correctly.

Syllabus sections

Core » Topic 3: Genetics » 3.4 Inheritance

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