Question

The transition of life on land presented many challenges for organisms that were originally living in aquatic habitats. List three ecological challenges and the adaptations that plants and animals each evolved separately for coping with life on land. The challenges may (but not necessarily overlap), but the corresponding adaptations must be specific to either plants or animals, not both. **PLEASE BE DESCRIPTIVE AND PROVIDE FULL SENTENCES**

Answer 1

Three ecological challenges-

1. prone to desiccation

2. More predators for animals and more competition for plants

3. Transport of materials in both plants and animals

Resultant adaptations-

1. Plants adopted many modes in order to save themselves from the dry environment available on the land. One obstacle was structural support. In water, organisms are buoyant and the effects of gravity are minimal. On land, however, if a plant is to grow tall, it needs to withstand the forces of gravity. Rigid cell walls developed to provide support, as did different types of supportive tissues, the woody tissue layers of trees are good examples. Hard cuticles, development of stomata underside and development of deep roots all solved the problem of desiccation. Deep roots helped the plants to obtain the water for all their needs and helped them not to get heated up under dry conditions present on the land.

Similarly, animals developed an efficient excretory system to prevent most of the water. They developed a large surface area to increase the loss of heat by radiation, which allows the animal to keep cool, developed such kind of skin that prevents water loss. Development of eyelids that allow them to adapt to vision outside of the water.

2. To avoid competition, plants use animals, wind and other mechanisms to disperse their seeds or spores away from the parent plants.

Similarly, animals developed many techniques to avoid predation like developmental of defensive structures, group living, mimicry, camouflage, improved vigilance etc.

3. A second challenge to life on land was the distribution of water and other materials to each cell. In aquatic forms, transport occurs directly from the surrounding environment. During plant evolution, systems of “conducting vessels i.e tube-like structures developed that function to transport materials up, down, and around the plant. These structures are named xylem which is used for the transport of water and phloem used for transport of food.

An efficient circulatory system developed in land plants which transported materials across various organs such as the development of red blood cells and haemoglobin. Similarly, gills were replaced by lungs for the exchange of gases.