1.2. Cells as the basic units of living organisms
A subsection of Biology, 9700, through 1. Cell structure
Listing 10 of 330 questions
Table 1.1 lists cell structures that can be found in eukaryotic cells or prokaryotic cells. Some of these cell structures can be found in both types of cell. Complete the table using a tick (3) to show that the cell structure can be present in a particular type of cell and a cross (✗) to show that the cell structure cannot be present. Put a tick or a cross in every box. The top row has been completed for you. Table 1.1 cell structure eukaryotic cells prokaryotic cells nucleus ✗ Golgi body circular DNA 70S ribosome All cells have a cell surface membrane. shows a transmission electron micrograph of part of two adjacent animal cells, cell 1 and cell 2. R cell 1 cell 2 ×300 000 In the space provided, draw a diagram of the region in the box labelled R on . Your diagram should show the four dark lines. Label the diagram to identify what is shown by the dark lines and each of the three spaces between them. space for diagram: Mitogens are short chains of amino acids that function as cell-signalling molecules. Mitogens are released from secretory cells and travel in the blood to target cells, where the mitogens bind to cell surface receptors. The target cells respond by progressing from the G1 phase to the S phase of the mitotic cell cycle. Outline what happens in the G1 phase and S phase of the mitotic cell cycle. G1 phase S phase As a result of mutation, the production and release of mitogens into the blood can be greatly increased. Suggest a possible consequence for target cells of increased concentrations of mitogens in the blood.
9700_m23_qp_22
THEORY
2023
Paper 2, Variant 2
View
The pathogen that causes cholera is a prokaryote. shows an electron micrograph of the pathogen that causes cholera. Name the type of electron microscope used to produce the image shown in . Name the species of prokaryote that causes cholera. The passage contains a description of the main features of prokaryotic cells. There is one factual error in the passage. Prokaryotic cells are unicellular and generally between 1 μm and 5 μm in diameter. Prokaryotes do not have organelles surrounded by double membranes. They do have cell surface membranes, 70S ribosomes and a cellulose cell wall. The DNA of a prokaryotic cell is circular and is found free in the cytoplasm rather than enclosed in a nuclear envelope. Identify and correct the factual error in the passage.
9700_m24_qp_22
THEORY
2024
Paper 2, Variant 2
View
Questions Discovered
330