Biology 3: Life On Earth Flashcards
Species
Basic categories of biological classification, composed of individuals that resemble one another, can breed among themselves, but cannot be like the members of species
Habitat
The physical surroundings of an organism
Adaptation
The way in which species changes over time to become better able to survive in its environment
How do organisms thrive in where they live
The organisms that live in a habitat are dependent on their environment and other species living there. They depend on other species for food and compete with each other resources
Habitat
The physical surroundings of an organism
Competition
Result of more that one organism needing the same source, which may be in short supply
How are feeding relationships shown
The feeding relationships of organisms are shown in a food web
How do feeding relationships and habitats link
The feeding relationships or organisms in a habitat are often complex. They depend on each other, often in ways other than just providing food. This is called interdependence
Interdependence
Relationship between several organisms that depend on one another
How does interference affect a species
Because of their interdependence, any change that affects one species in a food web is likely to affect all species in that food web
How can an animal become extinct
A species can become extinct of it is unable to adapt tabloid lay to a change in environment e.g climate change
Extinct
A species that no longer survives
How does the removal of habitats affect species of
Removal of habitats due to human activity threatens species, e.g the Siberian tiger and mountain gorilla
How can the introduction of a new spices lead to extinction
The introduction of a new species can lead to extinction of the species is a competitor, predator or causes disease
How can extinction affect different organisms
The extinction of a species in a habitat will affect other organisms in the food web and may cause them also become extinct
What are nearly all organisms dependent on
Nearly all organisms on earth are dependent on the energy from the sun
How do plants use photosynthesis
- Plants abort a small percentage of the energy from sunlight to produce their own food by photosynthesis.
- Plants restore this energy in chemicals that makes up the plants’ cells and tissues
Photosynthesis
Process carried out but green plants in which sunlight, carbon dioxide and water used to produce glucose and oxygen
How do it her organisms get their energy from the Sun
Other organisms get their energy by eating plants. Almost every food chain begins with a plant absorbing energy from the sun
What is transferred through the food chain
Energy is transferred form one organism to the next along a food chain
Describe the energy Change throughout each organism in the food chain
Only a small percentage of the energy transferred remains in each organism’s body. In the transfer from a plant to an animal, some energy is lost because:
• some parts of the plant aren’t eaten or can be digested by the animal.
• the animal uses some of the plants energy for respiration. During respiration, some energy is lost as heat
• the waste products of an animal, for instance urine, contain some energy
Why are the length of food chains limited
Energy is lost at each level of a food chain. So the length of food chains is limited - they are rarely longer that four or five organisms
How do calculate the efficiency of energy transfer at any level using the equation
Percentage efficiency= (energy in tissues x energy as food eaten) x 100
How does energy transfer efficiency continue after an organism dies
Energy transfer continues after an organisms has died. Microorganisms such as bacteria and fungi feed on dead or decaying organisms, called decomposers
Decomposers
In a food chain, an organism such as fungus that uses materials from dead or decaying matter
What are detritus
Partly decayed material
Detrivores
In a food chain, an organism such as an earthworm that breaks down dead or decaying matter into smaller particles
Why is carbon important
Carbon is the key element of the chemicals that make up all living things. It is continually recycled through the carbon cycle
Explain the carbon cycle
- Carbon enters the carbon checked as carbon dioxide from the air plants fix this carbon, so that it can be used and sores by organism for photosynthesis
- Carbon is returned to the air in the following ways:
- as a product of respiration, when plants and animals release energy from food
- through the decomposition of dead organisms by soil microorganisms such as bacteria and fungi
- by combustion of organic material
Why is the nitrogen cycle important to animals and plants
- Plants take up nitrogen from the soil through their roots, in the form of nitrogen compounds including nitrates. These are converted into proteins
- Protein is important nutrient in animals’ diets. It passes along food chains as animals eat plants and other animals
- Nitrates are released back into the soil as animals excrete waste, and as plants and animals die and are decomposed by microorganisms
Name the two ways in which nitrogen enters the nitrogen cycle
- Nitrogen molecules in the air age split by lightning. Nitrogen atoms the combine with oxygen in the air to form nitrates, which are washed into the soil by rain
- Nitrogen-fixing bacteria, found in the soil and in the roots of leguminous plants such as bean and peas, convert nitrogen in the air into nitrates
How does nitrogen leave the nitrogen cycle
Nitrogen leaves the nitrogen cycle when denitrifying bacteria convert nitrates in the soil into nitrogen gas. This process is called denitrification.
How is environmental change measured
Environmental change is measure using:
- non-living indicators, e.g. carbon dioxide levels, temperature and nitrate levels
- living indicators, e.g. phytoplankton (microscopic aquatic plant-like organisms), lichens (dual organisms made up of a fungus and alga living together) and aquatic organisms such as mayfly larvae
Biotic index
- Scientist monitor environmental change from a local through to a global scale
- Observation of some living indicators can give us very precise information about levels of pollution and environmental change. This is called biotic index. E.g. mayfly larvae need high levels of oxygen in the water, so will indicators very low levels of pollution
How does non-living indicator data benefit scientists
- Interpretation of data from non-living indicators and living indicators helps scientists to monitor environmental change and trends over a period of time.
- Measurements using non-living indicators, e.g. CO₂ in air and water, are monitored continuously. We can also look at historical levels from CO₂ trapped in ice.
Evolution
Change in species over a long period of time
What is the relationship between variation and evolution
The changes involved begin with variation between individuals. Variation has has genetic and environmental causes
Where are evidence of animals found
- Evidence of how organisms changed over time is found in fossils. Fossils are the remains of organisms, or other traces of their lives such as footprints or eggs, that have turned to rock.
- Scientists can date fossils from the layer of rock they are found in.
What is and what are the properties of a mutation
- A mutation is a change in the genetic information in a cell. A mutation will result in a change in the characteristics
- Mutations can occurs DNA is copied during the production of new cells.
- If a mutation occurs as sex cells are produced, the mutation is passed to the offspring
- Most mutations are harmful, by sometimes new, useful characteristics are produced. Useful mutations will be passed throughout the population
Gene pool
The complete set of alleles in a populations; a larger results in greater genetic variation
Fossil record
The information obtained over the years from fossil collections
How does genetic variation benefit organisms
Because of tentative variation, some individuals will have characteristics that give them a better chance of survival than others.
Natural selection
Process by which characteristics that can be passed on in genes become more common. In a pollution over many generations (which are likely to give the organism an advantage that makes it more likely to survive)
Selective breeding
Choosing organisms with desired characteristics to breed with one another
Name the ways that humans have been involved in selective breeding
- Choosing the individuals with the characteristics that are closest to those required
- Breeding these (and preventing other individuals from breeding)
- Repeating the process over several generations
Why is natural selection important part of the evolutionary process?
It residents in an organism that is better able to survive in terms of:
- Reproduction, which will lead to an increase in the number of individuals displaying the characteristics in later generations
- Competition with other animals, e.g. catching food, escaping predators, resistance to disease
How does evolutionary change take place
- Over a long period of time advantageous genes chosen by natural selection are likely to become the norm in the population.
- However, natural selection can be seen in operation over short periods of time. E.g the development of bacteria slushy have become resistant to antibiotics
Name the 2 factors that influences the rate at which evolution takes place
- When the environment changes, only those organisms that are best adapted, or can re-adapt, will survive
- If organisms become isolated, for instance in an island, natural selection will act independently on the different populations. Over time the populations will become distinct and no longer able to reproduce with each other. They will be new species
In the search for evidence, how do scientists investigate the relationship between organisms?
- Examining the fossil record
- Observing similarities and differences in physical features, e.g. skeletons, flowers
- Analysing DNA sequences (more closely related organisms have more DNA sequences in common)
What evidence is their to support the theory of evolution
- The simplest organisms are found in the earliest rocks
- More recent fossils have features that look like adaptations or developments of those of older organisms
- DNA analysis of today’s organisms has confirmed prediction made from the fossil record, including when branches in the tree of life occurred
Explain the theory of evolution
- The theory of of evolution was proposed by Charles Darwin and Alfre Russel Wallace in 1859.
- The theory was based on Darwin’s observations on the Galápagos Islands. The islands are volcanic, so organisms on the islands must have arrived, at some point, from the mainland
- Darwin observed that organisms, which as mockingbirds, were similar but had slight differences to those on the mainland. The mockingbirds were also different from one island to the next.
- Drawings idea that species were not fixed, but could change over time, was the result of his observations and his creative thinking
- By contrast m, there was no evidence to support Larmarck’s theory. Larmarck suggested that animals acquired characteristics during their lifetime that were then passed on to their offspring
Biodiversity
The variety in terms of number and range of different life forms in an ecosystem
What 3 factors come under biodiversity
- The number of different species
- The range of different rules of organisms, e.g. plants, animals, microorganisms
- The genetic diversity (variation) within each species
Name a habitats with a very high biodiversity and what they are used for
Tropical rainforests and could be valuable to us as food crops or Medicines
Mass extinction event
The extinction of a large number of species at the same time
Why are species becoming extinct
- Species are now becoming extinct more rapidly than at any other time, except for mass extinction events seen in the fossil record. It is thought that this is connected with human activity, as organisms are hunted and their habitats are destroyed.
- Climate change will accelerate this rate of extinction
How are organisms classified
- A kingdom is a large group with many organisms but fewer characteristics in common
- Moving down from the kingdom, the groups get smaller and have fewer organisms with more characteristics in common
- The level identifying the individual type of organism is the species
Sustainability
Measure of whether a resource or process we use now will still be able to be used by future generations
How does sustainability affect biodiversity
To ensure sustainability, we need to maintain biodiversity. The loss of a single species removes a food supply and can have a big impact on the whole ecosystem
What is Intensive monoculture crop production
Maximises crop yields but it is not sustainable. It reduces the biodiversity of the field by: growing just one crop species; removing hedgerows to create huge fields for planting; spraying crops with herbicides and pesticides
Name 3 ways that we can improve sustainability in product manufacture
- Using as little energy as possible and animal packaging
- Using locally available materials and limiting transport of the product
- Creating as little pollution as possible
How does the life cycle assessment track the environmental impact of a product
Sourcing of raw materials ➡️ manufacture ➡️ transport ➡️ use ➡️ disposal
Biodegradable
A material that can be broken down by microorganisms
What is the disadvantage of biodegradable packaging
It’s is best to reduce all types of packaging, as even biodegradable materials break down very slowly, in landfill sites, produce carbon dioxide, and require energy to produce and transport