Question 1
1.1. Briefly explain the following terms:
1.1.1. Essential element
An essential element is any element required by plants for their growth and reproduction. These
elements are necessary because plants cannot complete their life cycle without them, and they play
specific roles in metabolic functions. (Hopkins & Hüner, 2008, p. 65)
1.1.2. Carbon partitioning
Carbon partitioning refers to the allocation of carbon fixed during photosynthesis between different
plant parts (e.g., leaves, stems, roots). This process ensures that energy is distributed where it is most
needed. (Hopkins & Hüner, 2008, p. 151)
1.1.3. Sink activity
Sink activity describes the ability of certain plant tissues (sinks), such as roots or growing leaves, to
accumulate photoassimilates (sugars and other carbon compounds) from the phloem. (Hopkins &
Hüner, 2008, p. 159)
1.1.4. Critical concentration
The critical concentration is the level of a nutrient in plant tissue that, when below a certain threshold,
leads to visible deficiency symptoms and stunted growth. (Hopkins & Hüner, 2008, p. 67)
1.1.5. Mucigel
Mucigel is a gel-like substance produced by the root cap cells in plants. It plays a crucial role in
protecting root cells, facilitating nutrient uptake, and enhancing root growth. (Hopkins & Hüner,
2008, p. 56)
1.2. Define mycorrhizae, citing the two main classes and the differences between them.
Mycorrhizae are symbiotic associations between fungi and plant roots. The two main types of
mycorrhizae are arbuscular mycorrhizae (AM) and ectomycorrhizae (ECM). AM fungi penetrate the
root cells, forming structures inside, while ECM fungi surround the root but do not enter the cells.
The main difference lies in how they associate with the plant roots. (Hopkins & Hüner, 2008, p. 57)