B3 Flashcards
What is a species?
A group of organisms that can reproduce to create fertile offspring
What is adaptation?
The adjustment to a habitat to ensure survival
Animals and plants in a habitat are all part of one large system called a…
Food web
Describe interdependance
The dependance of organisms on each other with the change of levels of one having a massive impact on the rest of the food web
Name 3 ways do animals become extinct
By failing to adapt to a changing environment
Threat to habitat from humans
Introduction of a new species
How is energy transferred along the food chain from the sun?
Plants absorb energy from the sun, and this energy is transferred through food chains as animals begin to consume each other
How is energy lost along the food chain?
Some parts of organisms cannot be digested
Some energy is lost through respiration and movement
It can also be lost through excretion as waste products have energy
How is energy transferred even after an organism dies?
Decomposers (fungi, bacteria) break organisms down into detritus (partly decayed material) and detritivores (worms, woodlice) eat it and break it down more
Describe the carbon cycle
Carbon exists in the air mainly as carbon dioxide. Plants use this for photosynthesis. Carbon then passes into organisms as they eat plants. It is then returned to the air as carbon dioxide through respiration, the death of organisms (decomposers breaking them down respire) and combustion of organic materials
How is nitrogen from the air transferred into soil?
Lightning and nitrogen fixing bacteria in the roots of legumes fix nitrogen in the soil
How is nitrogen in the soil used?
It is absorbed by plants which is then passed on to animals that eat the plants
How is nitrogen put back into the atmosphere?
The break down of dead organisms and faeces by bacteria turns it into ammonia, which is then turned into soil nitrates again by nitrifying bacteria. Then denitrifying bacteria in the boggy soil return the nitrates back into nitrogen in the air
What are indicators of environmental change?
Non living indicators - carbon dioxide and nitrate levels or temperature
Living indicators - decreasing number of small organisms
How can we see the development of organisms over millions of years?
Genetic variation and fossils
How does evolution happen?
A mutation of a gene in an organisms’ sex cell can cause a new characteristic that can be passed on to offspring. This can continue to be passed on if reproduction occurs between organisms with this characteristic
What is natural selection?
Organisms in environments may have different traits due to evolution. Organisms with a trait is useful will have a greater survival rate of animals that have the trait and therefore more likely to reproduce. Organisms failing to survive in the new habitat will die as off leaving a new species
How can traits varying benefit organisms?
Make it easier to compete with other organisms - avoid prey, catch food, increase disease resistance
What happens in the selective breeding process?
2 organisms with the same desirable trait are selected
They are bred to create offspring
Offspring that have this desirable trait are then bred with other organisms with same desirable trait
This goes on for several generations
Evidence for evolution
Similarities in some parts of DNA sequencing in species showing they have a common ancestor
The simplest organisms are found in the earlier rocks and more complex organisms in newer rocks
DNA analysis today has confirmed that prediction made from fossils were correct
Describe Darwin’s theory about variation in animals
Darwin said that random mutations in animals genetic occurred leaving to a new characteristics emerging in offspring and as the animal reproduces the trait is passed on. He called it the theory of evolution
Describe Larmarck’s theory about variation in animals
Larmarck stated an animal adapted to its environment and passed on that trait to its offspring
e.g. giraffes grew long necks to reach plants higher up and then the giraffes offspring already had long necks when they were born
Why is Darwin’s theory accepted over Larmarck?
There is evidence of the theory of evolution and not for Lamarck’s theory
What is biodiversity?
The variety of life on Earth or in a habitat
How can biodiversity be measured in a habitat?
The number of different species
The range of organisms (plants, animals, micro-organisms)
The genetic variation within each species
What is a kingdom?
A large group of many organisms but few characteristic in common (e.g. mammals, reptiles)
What is sustainability?
The ability to meet today’s needs without hindering future generations from meeting theirs
How do we increase sustainability?
Maintaining biodiversity as all organisms are very dependant on each other
Limit our impact on wildlife and their habitats
Supporting ecosystems
What is the Life Cycle Assessment?
The assessment that tracks the environmental impact of a product from:
sourcing raw material → manufacture → transport → use → disposal
How can we increase the sustainability of a product manufacture?
Use as little energy and packaging as possible
Use more locally available materials
Create as little pollution as possible
