B2 Flashcards
Describe the nitrogen cycle
1.Nitrogen gas is converted to nitrate compounds by nitrogen-fixing bacteria in soil or root nodules. Lightning also converts nitrogen gas to nitrate compounds. The Haber process converts nitrogen gas into ammonia for use in artificial fertilizers. Ammonia is converted to nitrates by nitrifying bacteria in the soil
2.Plants absorb nitrates from the soil and use these to build up proteins. The plant may be eaten by an animal, and its biomass used to produce animal protein
3.Urea and egested material is broken down by decomposers. This results in nitrogen being returned to the soil as ammonia
Decomposers also break down the bodies of dead organisms resulting in nitrogen being returned to the soil as ammonia
4.In some conditions denitrifying bacteria in the soil break down nitrates and return nitrogen to the air. This is usually in waterlogged soil. Improving drainage reduces this effect, making the soil more fertile.
What is the order of classification of animals?
kingdom phylum class order family genus species ‘Kevin plays clarinet or flute - grotty sound!’
Name the arthropods and the number of legs
Insects (6 legs) Arachnids (8 legs) Crustaceans (10 to 14 legs) Myriapods (centipedes and millipedes – more than 20 legs).
Describe two classes of classification system
Classification systems can be artificial. They use obvious differences in features so that the organism can be identified.However, these classification systems may not accurately reflect the evolutionary relationships between organisms. Today, scientists can sequence the DNA of many organisms relatively easily. Computer programs compare the DNA sequences of different species to look for similarities and differences. This allows evolutionary trees to be made.
Describe 3 characteristics that define a species/ Similar species and why they may look vastly different from similar species
A species is a group of organisms that can interbreed to produce fertile offspring. Similar species tend to live in similar habitats. Closely related species share a relatively recent ancestor- a ‘common ancestor’. If they live in different type of habitat, closely related species may have different features.
Describe the binomial system
In the 18th century, Carl Linnaeus started the modern system of putting species of organism into certain groups and giving them scientific names. The first part of the name tells you the genus, while the second part of the name tells you the particular species in that genus.
Why can it be difficult to class some organisms into species? (2 Reasons)
Some organisms can only reproduce asexually, while some species can interbreed to produce hybrids.
This is an evolutionary tree. Who shares common ancestors with who?
. Th
For example, the Human and the whale had common ancestor. This ancestor then had a common ansestor with the Dimetrodon. Everything mentioned there had a common ancestor with the group of four on the far right. They all have one common ancestor, probably from a distant past.
Describe :
A- producers
B- primary consumers
C- secondary Consumers
D- scavengers
E- Decomposers
A- Green plants and algae. They make food by photosynthesis.
B- Usually eat plant material - they are herbivores. For example rabbits, caterpillars, cows and sheep.
C- Usually eat animal material - they are carnivores. For example cats, dogs and lions.
D- Feed on dead animals. For example, crows, vultures and hyenas are scavengers.
E- Feed on dead and decaying organisms, and on the undigested parts of plant and animal matter in faeces.
Which was does energy travell in a food chain or wab (think arrows)
The animal points at whats eating it!
Energy is transferred along food chains from one stage to the next. Why does the amount of available energy decrease from one stage to the next?
Not all of the energy available to organisms at one stage can be absorbed by organisms at the next one.
- Energy released by respiration is used for movement and other life processes, and is eventually lost as heat to the surroundings
- Energy is lost in waste materials, such as faeces.
What is biomass and why can there be problems measuring it?
Biomass means the dry mass of living material at a stage in a food chain,
- There may be problems measuring dry biomass, such as a need for the organism to be dead
- An organism may belong to more than one trophic level (stage of a food chain), so it cannot easily be represented by one bar.
Describe why nitrogen and nitrates are needed
Nitrogen is essential for the formation of amino acids in proteins.Because nitrogen is so unreactive, it cannot be used directly by plants to make protein. Only nitrates are useful to plants, so nitrogen must be converted to nitrates.
Describe the carbon cycle.
- Carbon enters the atmosphere as carbon dioxide from respiration and combustion.
- Carbon dioxide is absorbed by producers to make carbohydrates in photosynthesis.
- Animals feed on the plant passing the carbon compounds along the food chain. Most of the carbon they consume is exhaled as carbon dioxide formed during respiration. The animals and plants eventually die.
- The dead organisms are eaten by decomposers and the carbon in their bodies is returned to the atmosphere as carbon dioxide. In some conditions decomposition is blocked. The plant and animal material may then be available as fossil fuel in the future for combustion.
What may animals compete for? (3 things)
food
water
space
What may plants compete for? (3 things)
light
water
minerals
What is a ‘niche’?
A niche is a particular place or role occupied by an organism within an ecological community. Similar species will occupy similar niches. For example, red squirrels and grey squirrels are two different species. They occupy similar but slightly different niches.
What are the two main types of competition, and which is likely to be more significant?
- *interspecific competitio**n, which happens between individuals of different species
- *intraspecific competition**, which happens between individuals of the same species.
Intraspecific competition is often more significant than interspecific competition., and more likely to affect competing populations.
What is going on here and why?
No other cat is so dependent on a single prey species, which is why there is such a clear pattern of interdependence between the two populations.
If the prey population grows, predator numbers will respond to the increased food supply by increasing as well. But the growing predator population will eventually reduce the food supply to the point where it can no longer be sustained.
Notice that the cycles of each population are out of phase with each other - a peak in one population is followed later by a peak in the other population.
