Dodder (Cuscuta) is a parasitic vine that grows on other plants, such as clover or tomato plants. It has very little chlorophyll and obtains nutrients directly from the plant it grows on.
Select the term used to describe the plant that the dodder grows on in this relationship.
Explain why the dodder grows specialized root-like organs (haustoria) into the phloem of the other plant.
Scientists investigated two different species of dodder growing on a host tomato plant. One species of dodder (Cuscuta reflexa) is slightly green, while the other (Cuscuta europaea) is pale yellow.
They supplied the host tomato plant with carbon dioxide containing radioactive carbon (14C^{14}\text{C}14C). The radioactive carbon dioxide was not supplied to the dodder.
They then measured:
The table shows their results:
| Species of dodder | Chlorophyll content in mg/g of tissue | Percentage of sugar in the dodder that is radioactive (%) |
|---|---|---|
| Cuscuta europaea (pale yellow) | 0.05 | 95 |
| Cuscuta reflexa (slightly green) | 0.25 | 40 |
Explain why sugar in the dodder becomes radioactive.
Explain the relationship between the chlorophyll content and the percentage of radioactive sugar in each species of dodder.
82 exam-style questions on OCR GCSE Biology 2.1 Supplying the cell, covering 2.1.1 Transport across cell membranes, 2.1.2 Mitosis and the cell cycle, 2.1.3 Importance of cell differentiation, and 2.1.4 Stem cells. Each one has a worked solution and a mark scheme showing where the marks go.