B.3.2

31 flashcards · Biology · by Michael Katsikas

1. The role of an organism in an ecosystem

   Niche

2. Habitat

   The natural environment a species lives

3. Biodiversity

   The diversity of plant and animal life in a particular habitat

4. Organisms and their interactions with biotic and abiotic factors

   Ecosystem

5. Microhabitat

   A small area of the habitat

6. A group of organisms of the same species living and breeding together in a habitat

   Population

7. Community

   All the populations of all the different species or organisms living in a habitat at any one time

8. What are abiotic factors? Give some examples.

   Non-living elements of the habitat of an organism including those related to the climate and soil (edaphic): amount of sunlight temperature rainfall drainage (soil) pH (soil) oxygen availability (in aquatic environments)

9. The living elements of a habitat that affect the ability of a group of organisms to survive there

   Biotic factors

10. What is the biosphere and biomes?

    Biosphere is all areas of the surface of the Earth where living organisms survive they’re divided into smaller parts distinguished by similar climates and plant communities called biomes (major ecosystems of the world)

11. Succession

    The process by which the communities of organisms colonising an area change over time

12. What does primary succession start with?

    Starts with empty inorganic surface such as bare rock or a sand dune

13. What is the first stage of succession?

    Colonisation: process by which new species spread to new areas

14. What organisms are the first to appear in succession and why?

    Opportunists / pioneer species like algae, mosses, fungi as these organisms can penetrate the rock surface by: - dissolving rock with acids they secrete - penetrate tiny cracks with root hairs and hyphae

15. What happens as the soil layer continues to develop during succession?

    as soil layer develops, more water and nutrients are kept and become available for plant roots meaning less resistant species survive gradually, larger plants can be supported and species diversity increases resulting in an increase in diversity of animals that can be supported

16. When do we reach a climax community?

    A climax community is reached in which the biodiversity and range of species are generally constant it’s self sustaining and the most productive group of organisms the environment can support

17. A sub-climax community where succession has been held back / deflected by human activity climax community can develop when humans move away

    Plagioclimax

18. What is secondary succession and when does it occur?

    The development of an ecosystem from existing soil clear of vegetation occurs after fires, floods, disturbances caused by humans there are a higher number of plants from the start

19. What factors does the time taken to go from bare Earth to a climax community depend on?

    temperature rainfall soil fertility

20. What is a climatic climax community?

    the only climax community possible in a given climate

21. What are some adaptations of plant populations that grow well in low light level habitats (such as plants in understory of rainforest) ?

    reproduce early in the year to avoid shade of larger plants in summer extra chlorophyll different ratio of photosynthetic pigments sensitive to lower light levels very large leaves to absorb light

22. How are animals indirectly affected by light levels?

    as a result of distribution of food plants seasonal light changes affect reproduction patterns in some animals are affected by 24 hour cycle of light and dark and this influences natural rhythms that control much animal physiology and behaviour

23. What are 2 main strategies animals evolved to to help them deal with extreme temperatures?

    animals have evolved behaviours and physiological adaptations

24. What is the relationship between strong prevailing winds and the number of species that can survive in such conditions + why?

    Wind increases cooling and water loss from the body so increasing environmental stress Fewer species can survive in areas with strong winds Gales and hurricanes cause extreme damage to populations; whole woodlands may be destroyed and communities of plant and animal life within them lost

25. How do organisms survive in water where there are currents?

    flow with the current be strong swimmers be able to attach to a surface and resist force of water

26. What is the adaptation for plants that can survive in waterlogged soil?

    Some plants are adapted to waterlogging, such as species that grow in wetlands. Usually, such plants can survive waterlogging by forming aerenchyma. These are air spaces in the stems, roots or leaves. When shoots conduct aerobic respiration, they transport oxygen to the aerenchyma air pockets in the roots. This gives the roots their own reserve supply of oxygen. Rice is the only economic crop that grows optimally in waterlogged soils and this thanks to its ability to form aerenchyma. Other plan…

27. What type of plant populations survive on sand and how?

    https://sand-boarding.com/sand-plants/#:~:text=Below%2C%20six%20strategies%20that%20plants%20have%20adopted%20in,fleshy%20stems%20that%20store%20water.%20...%20More%20items

28. What is the pattern in a prey population where there are no predators?

    The prey population will start growing without control, over all other species, endangering the predator-prey equilibrium of other species, driving the ecosystem to a possible collapse.

29. Define territory

    Territory is an area held and defended by an animal (plant as well, but to a lesser extent) or group of animals against other organisms, which may be of the same or different species.

30. Examples of density-independent factors

    (Density independent-factors are abiotic factors that affect the growth of a population regardless of its size). Fires Natural disasters (earthquakes, floods, tornados) Effects of pollution Weather Human activities Physical and chemical phenomena Flooding

31. Examples of density-dependent factors

    Competition: Habitats are limited by space and resource availability, and can only support up to a certain number of organisms before reaching their carrying capacity. Predation: Many populations are limited by predation; predator and prey populations tend to cycle together, with the predator population lagging somewhat behind the prey population. Parasitism: Parasites can reduce the fitness and survival of their hosts, especially when the host population is dense and the parasites can spread e…