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| Biology B2 Flashcards | . |
| Classification | Classification systems help us to understand how organisms are related (evolutionary relationships) and how they interact (ecological relationships). NATURAL classification is based on evolutionary relationships and genetic similarities. ARTIFICIAL classification is based on appearance and is used to identify organisms. 1. Kingdom 2. Phylum 3. Class 4. Order 5. Family 6. Genus (closely related species) 7. Species (a group of organisms that can breed to produce fertile offspring). Many organisms have characteristics of multiple groups. Scientists may have to adapt the classification system to fit new findings such as a new species. |
| Hybrids & Asexual | Asexual Reproduction - an organisms reproduces by making a copy of itself, they do not fit the definition of a species because there is no interbreeding (bacteria). Hybrids - these are infertile so they aren't a new species - which makes them difficult to classify. When you interbreed a male from one species with a female from another, you will get a hybrid. |
| The Binomial System | The binomial system gives everything a two part Latin name. The first part is the genus and the second part is the species. This allows scientists from all over the world to refer to a species by the same name. Humans are homo sapiens, homo = genus, sapiens = species. |
| Pyramids of Biomass |
Biomass - The total weight of organisms in a given area. Each trophic levels shows the mass of the living material at that stage of the food chain. Biomass pyramids are always almost pyramid shaped because biomass is lost at each stage. To construct a pyramid of biomass you first need the dry mass which means you have to kill the animal and let all the water dry out which is unethical and will take a long time. It can also be difficult to construct as some organisms feed on more than one trophic level.
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| Pyramid of Numbers |
Each trophic level represents the number of organisms at that stage. Pyramid of Numbers can vary in shape.
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| Energy Transfer | Energy from the sun is the source of energy for all life on Earth. Plants used this energy to photosynthesis and this energy works it's way through the food chain when animals eat plants and then each other. Energy is lost at each stage by: Staying alive (respiration) Heat (most bodies must be a constant temperature which is normally higher than the surroundings) Egestion (food that can't be digested passes out as faeces) Excretion (waste product of bodily processes are released) Waste products and uneaten products can become new starting points for new food chains. |
| Energy Flow |
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| Competition and Niches | In order to survive and reproduce organisms must compete for the resources they need to survive.. Similar species in a similar habitat will have the closet competition because they will be competing for similar ecological niches. A niche is a particular place or role occupied by an organism within an ecological community. Inter-specific competition is where individuals from different species compete for resources. Intra-specific competition is where individuals from the same species compete for resources. Intraspecific competition has a bigger impact on organisms because individuals from the same species have exactly the same needs. |
| Prey & Predators | The population of any species is limited by the food available. If the population of the prey increases, so will the population of the predators. However, as the numbers of predators increase, the numbers of prey will decrease. |
| Parasites & Mutualism | PARASITES live off a host, they take what they need to survive and give nothing back, this often harms the host. MUTUALISM is a relationship where both organisms benefit. |
| Organisms & Adaptations | Adaptations are features that make organisms better suited to their environment. Organisms that are adapted to their environment are better able to compete for resources which means they are more likely to survive, reproduce and pass on their adaptations to their offspring. SPECIALISTS are organisms which are highly-adapted to survive in a specific habitat (giant pandas). GENERALISTS are organisms that are adapted to survive in a range of different habitats (black rats). Specialists will out-compete generalists in a stable habitat and vice-versa. Organisms that are adapted to live in seriously extreme conditions are called extramophiles. |
| Adaptations (Cold) | Organisms that live in cold environment have anatomical adaptions. These are: - a thick coat and layer of fat to trap air particles and insulate the body. - a large size but compact body shape to decrease surface area to volume ratio which reduces heat loss because less heat will be lost through the surface of the skin. Penguins have a counter-current exchange system in their feet. Blood vessels that carry blood to and from the feet carry it in opposite directions but these vessels pass close to each other which allows heat to transfer between them. Warm blood flowing into the feet heats up the cold blood returning to the heart. Their feet do stay cold but this stops this cold blood cooling down the rest of the body. Animals that like in cold climates may have behavioral adaptions. These can include: - huddling together for warmth - hibernating to save energy - migrate to warmer climates. |
| Adaptations (Hot) | Behavioral adaptations: - spending days in shade or underground to minimise heat gain. - being active at night - they can increase heat loss by bathing in water (evaporation) Anatomical adaptions: - small which increases surface area to volume ratio to lose more body heat. - large thin ears so more blood flow near surface so more heat can be radiated to surroundings. - storing fat in one place in body so not well insulated. Cacti have a rounded shape giving them a smaller surface area to volume ratio to decrease water loss. Also have cuticle (thick wavy layer) and spines instead of leaves to reduce water loss. Also they store water in their stems which allows them to survive in extreme drought. Also have shallow but extensive roots so water is absorbed quickly and over a large area. Some desert animals have specialised kidney which allow them to produce concentrated urine with little water content. Also, no sweat glands and spend time in underground burrows where air contains more moisture. |
| Charles Darwin's Theory of Natural Selection | 1. Darwin noticed that organisms in a species show wide variation and have to compete for limited resources. 2. He concluded that organisms that are best adapted would be more successful competitors and would be most likely to survive - 'survival of the fittest' 3. The successful are mos likely to reproduce and pass on their adaptations which made their offspring more successful. Over time, successful adaptions become more common in the population and the species evolves. Darwin's theory wasn't accepted because he couldn't explain how these adaptations appeared or were passed on. However, it is now more accepted because we know now that adaptions are controlled by genes and new adaptions arise because of mutations. Also, it went against common religious beliefs. |
| Lamarck's Theory of Acquired Characteristics | Lamarck argued that if a characteristic was used a lot by an animal it would become more developed and this would be passed onto their offspring. However, this was eventually rejected because the acquired characteristics do not have a genetic basis. |
| Speciation | Speciation is when organisms change so much because of natural selection that eventually a new species is formed. This happens when the same species change enough to become reproductively isolated. Reproductive isolation can be caused by geographic isolation. Here's how: - A physical barrier (a river in the way) - Different mutations create new features in the two groups of organisms and then natural selection works on these new features. - Since each side of barrier is different, the new features will be different so eventually they will have such different features that they cannot produce fertile offspring. |
| The Carbon Cycle |
The whole thing is powered by photosynthesis.
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