Abiotic and Biotic Factors

1. Abiotic and Biotic Factors

2. What are Abiotic and Biotic factors? Abiotic factors are non-living factors (environmental) which affect the survival of living organisms. Biotic factors relate to other living organisms in the environment which can affect the survival of other organisms.

4. Abiotic Factors: Water Salinity pH Temperature

5. Surviving Extreme Conditions: • One extreme condition faced by many plants in Australia is fire. Trees like Eucalypts have adaptations which help them to survive and regenerate after fire. These include: • Having thick bark which protects the inner cambium layer which is the tissue which produces new growth of bark and stem tissue needed for survival • Thick bark also protects the epicormicbuds which lie under the bark and is responsible for sprouting and regrowth. • Epicormic buds are kept dormant by apical dominance and it is only during fire when the apical dominance is removed by the loss of the top of the tree in fire. • Another survival mechanism for plants is having lignotubers. A lignotuber is a swelling at the base of a plant which holds dormant buds. These are usually found under the ground and are only activated when fire destroys the aerial portion of the plant.

6. Plant Adaptations to Arid Conditions: • Xerophytes are lovers of dryness. • To increase water uptake these plants increase their root length to find water. They either: • - extend out and around or • - Extend out and down • To reduce water loss these plants: • Have a thick cuticle which is waxy and impenetrable to water which help to minimise water loss to the environment. • They reduce the size and number of stomata to reduce transpiration rates and restrict opening times for water loss. • They also have the stomata not on the surface of the leaf but on in sunken pits which also aids in reducing the amount of water loss. • They have small leaves reducing the surface area for water loss. • Produce drought resistant seeds which remain dormant until heavy rain arrives.

7. Plant Adaptations to Aquatic Environments: Abiotic Factors which affect aquatic environments:

8. How does temperature, pH and light affect plant survival? Temperature: Water absorbs and releases large amounts heat with very little temperature change. Water tends to have a layered effect with hot water closer to the top whilst the coldest water is on the bottom. This layered effect creates multiple different environments for organisms to occupy. pH: pH is determined largely by the amount od dissolved carbon dioxide which forms carbonic acid in water. An increase in carbon dioxide will increase photosynthesis but as a result of the increase in pH many other organisms will die (such as fish) Light: Transparent water permits light to reach photosynthetic organisms Cloudy water prevents light reaching these organisms and could result in the death of the plants which in turn will affect the food supply for many other organisms in the food chain.

9. Hydrophytes: • A hydrophyte (water lover) is a plant that grows in or on water. • The adaptation these plants have include: • Air filled spaces in their tissue through which air can move from • aerial parts of the plant to submerged parts • Stomata are located on the upper surface of leaves that float on top of the water as the underside is only exposed to water. • In plants that are entirely submerged : • Diffusion occurs across the leaf surface which has a large surface area with very few stomata. • Spongy in the leaves and stems store oxygen produce by photosynthesis and this oxygen can then be used for cellular respiration.

10. Plant Adaptation to Salty Conditions: • Halophytesare lovers of salt. • Plants survive salinity by regulating the concentration of salt in the shoots. Plants do this by: • Having a higher osmotic pressure in their cytoplasm than other species • Control salt levels by: • - excluding salt form the leaves • - return salt to the roots • - diluting incoming salt by increased growth of • shoot • - shedding salt-laden leaves • - excreting salt through salt glands

11. Glossary Terms Abiotic Factors Biotic Factors Limiting Factors Tolerance range Distribution Adaptation Adapt to Hydrophyte Pneumatophores Hibernation Torpor Xerophytes Halophytes Lignotuber Epicormic buds

12. Complete the following: Key Questions: 7,10,11,12,13 Chapter Review Questions: 1,2,3,4,5,8,10