ecology Flashcards
why do food chains normally not have more than 5 organisms?
In a food chain, 90% of the energy is lost to cellular respiration and excretory waste products. Only 10% of energy is transferred from one trophic level to the next. Thus, there would be insufficient energy for the animals at the top of the food chain to survive.
how do decomposers help in the recycling of nutrients?
they break down complex nutrients in faeces and dead bodies of plants and animals to release carbon dioxide into the atmosphere and soluble mineral salts that dissolve in the soil water.
How does energy from the Sun enter the food web?
Light energy from the Sun is converted into chemical energy (i.e. glucose) by producers via photosynthesis. The glucose molecules made by the producers can be converted into other food molecules (e.g. protein and fats) and storage molecules (e.g. starch), which help to make up the producers and their growth. Energy from producers is passed from one trophic level to another via feeding.
How is it advantages for chickens to be reared in stacks of cages where they cannot roam freely?
More energy is made available for humans. As the chickens cannot roam around freely, less energy is lost to aerobic respiration and muscle contraction and relaxation. Hence, the chicken can use the saved energy for growth, increasing their body mass.
