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2.1 Supplying the cell

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Question 23

Rhizobium is a genus of bacteria that associates with the roots of legume plants, such as clover and peas. The bacteria live inside specialised structures called root nodules. Here, they convert atmospheric nitrogen gas into ammonia, which the plant can use, while the plant provides the bacteria with carbohydrates.

a.

Which term describes the relationship between Rhizobium bacteria and the host legume plant?

  • mutualist
  • parasite
  • predator
  • decomposer
[1]
b.

Complete these sentences about how the host plant and the bacteria supply each other with nutrients.

Use words from this list:

active transport, amino acids, chlorophyll, diffusion, phloem, photosynthesis, xylem \text{active transport, amino acids, chlorophyll, diffusion, phloem, photosynthesis, xylem} active transport, amino acids, chlorophyll, diffusion, phloem, photosynthesis, xylem
  • The host plant manufactures sucrose in its leaves during the process of _______.
  • This organic food is transported down to the root nodule cells through the _______ tissue.
  • Once inside the root nodule, the bacteria use these carbon compounds to assist in nitrogen fixation, producing _______ for the plant.
  • These nitrogenous products are loaded against their concentration gradient using _______ into the host's xylem tissue.
[4]
Markscheme

2.1 Supplying the cell Questions

  1. GCSE
  2. /Biology
  3. /2.1 Supplying the cell

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.

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