DP Biology (last assessment 2024)

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Question 23M.2.SL.TZ2.7a

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Date May 2023 Marks available [Maximum mark: 7] Reference code 23M.2.SL.TZ2.7a
Level SL Paper 2 Time zone TZ2
Command term Describe Question number a Adapted from N/A
a.
[Maximum mark: 7]
23M.2.SL.TZ2.7a
(a)

Describe the organelles and other structures in animal cells that are visible in electron micrographs.

[7]

Markscheme
  1. plasma membrane is thin layer forming outer boundary;
  2. cytoplasm fills space between membrane and nucleus;
  3. nucleus enclosed in nuclear membrane / nuclear membrane enclosing nucleus;
  4. chromosomes inside the nucleus/ visible during mitosis/ as rods (of condensed DNA);
  5. mitochondria with cristae/double membranes;
  6. (80S) ribosomes seen as dots free in cytoplasm/attached to rough ER;
  7. endoplasmic reticulum is a network interconnected tubes/ membranes /rough ER has ribosomes/ smooth ER does not;
  8. Golgi apparatus with stack of sacs/cisternae/curved or folded membranes/vesicles budding off;
  9. vesicles which are small membrane sacs;
  10. lysosome which contains enzymes/which is densely staining;
  11. any other organelle that would be visible correctly described;

Allow any point made on an annotated diagram.

Do not award any marks for just labels. Descriptions are needed.

Examiners report

Only the strongest candidates were able to describe, rather than state the function of the organelles. As with past questions about cell structure, many thought that a labelled diagram would suffice. Unfortunately, these generally scored zero unless they were well annotated.

Syllabus sections