Define the different categories of parasitic plants with examples (10 points).

Question

What is coevolution (10 points)? Explain by giving two examples (5 points).

Answer 1

The different categories of parasitic plants can be classified into three main groups: stem parasites, root parasites, and holoparasites.

1. Stem parasites: These plants obtain nutrients by attaching their modified stems to the host plants. Examples include dodder (Cuscuta spp.), which forms a tangled mass of orange-yellow stems, and mistletoe (Viscum album), known for its green, bushy appearance.

2. Root parasites: This category of parasitic plants attaches their roots to the host plants for nutrient absorption. An example is broomrape (Orobanche spp.), which lacks chlorophyll and depends entirely on host plants for survival.

3. Holoparasites: Holoparasites are complete parasites that do not carry out photosynthesis and entirely rely on host plants for nutrients. An example is Rafflesia arnoldii, which produces the largest flower in the world but lacks leaves, stems, and roots.

Coevolution is a process in which two or more species reciprocally influence each other's evolution over a period of time. It involves a close and long-term relationship between two species in which changes in one species drive evolutionary changes in the other species. Two examples of coevolution are:

1. Pollination by insects: Many flowering plants have evolved to attract specific pollinators such as bees or butterflies. The flowers produce nectar and have specific shapes, colors, and scents that cater to the preferences of these pollinators. In turn, the insects get food (nectar or pollen) from the flowers. This mutually beneficial relationship drives coevolution, where changes in flower characteristics influence the evolution of specific pollinators and vice versa.

2. Predator-prey relationships: The arms race between predators and prey is another example of coevolution. For instance, cheetahs, which are incredibly fast runners, have evolved their speed to catch swift prey like gazelles. In response, gazelles have developed their own adaptations, such as enhanced agility and keen senses, to evade predation. This ongoing coevolutionary process leads to the constant improvement of adaptations and counter-adaptations in both the predator and prey populations.