Biology Unit 1 Flashcards
What are the 2 ways that organisms can be related?
Evolutionary relationships (evolved from the same common ancestor)
Ecological relationships (different species have similar characteristics because they are competing
What were the 3 reasons that many people didn’t believe Darwin’s theory at the time?
It went against religious beliefs because his theory gave an explanation that didn’t need a “creator”
He didn’t know about genes and mutations so he couldn’t explain why new characteristics appeared or how they were passed on to offspring
There wasn’t enough evidence to convince many scientists because not many studies had taken place that supported his theory
What is the theory of evolution?
More than 3 billion years ago, life on Earth began as simple organisms from which all the more complex organisms evolved
What was Lamarck’s theory of evolution?
If a characteristic was used a lot by an organism, it would become more developed through its lifetime
This would then be passed on to the next generation
What is a mutation?
A change in an organism’s DNA
What were the 2 reasons that Darwin’s theory was accepted more than Lamarck’s theory as time went on?
There is now much more evidence that completely supports Darwin’s theory
Lamarck’s theory was rejected because if you dye a hamster’s fur pink and then it has offspring, its offspring won’t have pink fur
How do mutations affect natural selection?
If an individual has a mutation that makes them better adapted to survive in their environment (doesn’t always happen), they are more likely to survive, breed and pass on the characteristic that the mutation caused
What are evolutionary trees?
Diagrams similar to family trees that show how different species have evolved from common ancestors
Describe Darwin’s theory of natural selection
Individuals within a species show variation because of differences in their genes
Individuals with characteristics that make them better adapted to their environment have a better chance of survival so they are more likely to breed successfully
This means that the advantageous characteristics are more likely to be passed on to offspring so a species will gradually evolve
What are the 3 advantages of GM crops?
Can increase yield of the crop making more food
Crops can be engineered to produce nutrients that are required by people in some developing countries
GM crops are being grown elsewhere in the world without any problems already
Describe how embryo transplanting works
Sperm is taken from a good father and egg cells are taken from a good mother
The sperm is used to artificially fertilise an egg cell
The embryo is split many times to form many clones before the cells become specialised
These cloned embryos will be implanted into lots of other cows where they will be grow into offspring that will be clones of each other
What are the 3 disadvantages of GM crops?
GM crops can reduce the number of weeds and flowers which also has many knock-on effects that reduce biodiversity
Many people are worried that a lot of people could have allergies to the GM crops
The transplanted genes could be picked by other unwanted species of plants like weeds
What is genetic engineering?
Altering an organisms genes in order to change its characteristics
What are the 3 issues of cloning?
Leads to a reduced gene pool (fewer different alleles in a population)
Cloned animals are not usually as healthy as normal ones
People worry that humans will be cloned in the future and this would lead to many serious unsuccessful attempts
Describe how cuttings work
Gardeners can take cuttings from good parent plants and plant them to produce genetically indentical copies
This can be done quickly and cheaply
What are the 2 ways that plants can be cloned?
Cuttings
Tissue culture
Describe how tissue culturing works
A few plant cells are put into a growth medium with hormones and they grow into clones of the parent plant
This is very quick and can be done in very little space and be grown all year
What are the 2 advantages of cloning?
Can lead to a greater understanding of the development of the embryo
Could help preserve endangered species
Describe how genetic engineering is done
A useful gene is cut from one organism’s chromosome using enzymes
Enzymes are then used to cut another organism’s chromosome and then to insert the useful gene
Describe how adult cell cloning works
An unfertilised egg is taken and the nucleus (genetic material) is removed
A complete set of chromosomes is taken from an adult body cell
The egg cell is stimulated by an electric shock so that it divides like a normal embryo
It is then implanted into an adult female to grow into a clone of the original adult body cell
What are the 3 main ways that genetic engineering is used?
Genetically modified (GM) crops are engineered to make them resistant to viruses, insects and herbicides
Sheep have been genetically engineered to produce substances like drugs in their milk
Genetic disorders like cystic fibrosis are caused by faulty genes. Scientists are trying to treat these disorders by inserting working genes into sufferers (gene therapy)
What are the 2 ways of cloning animals?
Embryo transplants
Adult cell cloning
What is variation?
How members of the same species have differences
What causes genetic variation?
Members of the species have different genes because they have inherited mixes of genes from different sets of parents
What does the human cell nucleus contain?
All of the genetic material in the form of 23 pairs of chromosomes
What is environmental variation?
How offspring develop because of the conditions they grow up in
How something develops depends on both types of variation
Describe asexual reproduction
X-shaped chromosomes have 2 identical halves
Each chromosomes splits down the middle to form two identical sets of half-chromosomes
A membrane forms around each set and the DNA replicates itself to result in full chromosomes
What is the process of reproduction that happens with animals?
Sexual reproduction
What is the other natural use of asexual reproduction?
It is how all plants and animals grow and produce replacement cells
What is sexual reproduction?
Reproduction involving the fusion of male and female gametes resulting in offspring with a mixture of the parents’ genes
What are genes made from?
Long lengths of DNA
What do the chromosomes contain?
Genes
What is a gene?
The genetic material needed to control the development of one feature of the human
What is the process of reproduction that happens in plants?
Asexual reproduction
Describe sexual reproduction
The gametes have only 23 single chromosomes
The gametes of the father (sperm) fertilise the gamete of the mother (egg) to produce a fertilised egg that develops into the offspring
The genetic variation comes from the mixture of genetic material from the sperm and egg
What is an allele?
Different versions of the same gene are alleles
For example, brown and blue are alleles for the gene for eye colour
What are the 2 types of variation?
Environmental variation
Genetic variation
How do offspring inherit genes from their parents?
Genes from the parents are passed on to offspring on gametes (sex cells) which the offspring develop from
What is asexual reproduction?
Reproduction where there is only one parent so there is no mixing of genetic material resulting in offspring that are genetically identical to the parent
What 2 things speed up decay by microorganisms?
Plenty of oxygen available
Warm, moist conditions
What supplies the energy for all life processes?
Respiration
How do the nutrients that plants have taken from ground and passed up the food chain return to the Earth?
Decay
What happens as you go up a biomass pyramid and why?
The amount of biomass decreases as you go up the pyramid because some of the biomass isn’t consumed (inedible parts of the animal) and waste material isn’t consumed either
What is the carbon cycle?
The natural processes that cause carbon to be recycled over and over again
Describe how compost bins work
Most plant and animal waste can be made into compost
The compost is finely shredded to increase the rate of decay and put into the compost bin
The mesh sides allows air to get in to provide oxygen and the decomposition in the small area allows the area to become warm
Why are there not usually more than 5 species in a food chain?
At the top of the food chain, the amount of biomass that has been lost causes the biomass given to the top predator is minimal
What does the energy for almost all of life on Earth come from and why?
The Sun’s light
This is used in photosynthesis by green plants and algae which are then eaten by animals and so on meaning that the energy from the Sun is passed up the food chain
What are the 5 ways that the carbon is returned to the atmosphere?
When the plants and algae respite, carbon dioxide is released to the air
When animals eat the plants, the carbon is used to make carbohydrates, fats and proteins in the animals
Carbon dioxide is released when the animals respite
When plants, algae and animals die, microorganisms digest the remains and when they respire, they release the carbon dioxide
Microorganisms also digest the animal waste products and release the carbon dioxide when they respire
We also burn animal and plant waste and fossil fuels and release carbon dioxide in combustion
All carbon is returned to the atmosphere in some way
What is the first step of the carbon cycle?
Green plants and algae use the carbon dioxide in photosynthesis
What is a biomass pyramid?
A diagram that shows how biomass passes up a food chain and the amount of biomass going to each consumer
How do you draw a biomass pyramid?
You have to draw rectangular bars equal in height in top of each other with the consumer’s name inside each bar
The producer is at the bottom, the primary consumer is above it, the secondary consumer is above that and so on
The bar widths represent the amount of biomass (not number of thing) in proportion to the others
How does the carbon cycle start?
Carbon dioxide in the air
How does decay work?
The dead remains of the animals and plants and their waste products contain the nutrients originally taken from the ground
These materials are all digested (broken down) by microorganisms and return to the Earth as the basic elements and compounds
What is the main way that energy is lost from most animals?
Loss of heat because animals usually need to be hotter than their surroundings
What are extremophiles?
Microorganisms that are adapted to survive in extreme conditions
What are the 3 main adaptations of Arctic animals and why?
Minimal surface area to volume ratio to reduce heat loss
Thick layer of blubber and thick hairy cost for insulation and reducing heat loss (blubber can also act as an energy store for when food is scarce)
White camouflage to avoid predators or sneak up on prey
What are the 4 living factors that can change an environment that plants and animals live in?
A change in the occurrence of infectious diseases
Change in number of predators
Change in number of prey of availability of food sources
Change in the number or types of competitors
What are the 3 ways that environmental change can affect populations and how does this happen?
Population size increases because if number of prey increases, more food available for predators so number of predators increases
Population size decreases because there is more predators so less prey survive and so on or there is less food or there is more disease
Population distribution changes (some species move to more or different locations)
What are the 3 ways that environmental change can be measured with living indicators?
If there is less lichen in an area, that means that there will be more sulphur dioxide in the air so it can tell us about air pollution
If raw sewage is released into a river, there is more bacteria in the river which uses up the oxygen. Certain species like the mayfly larvae are sensitive to the amount of oxygen in the water and will only be in that water if the amount of oxygen is normal (no sewage)
Certain invertebrate species have adapted to live in polluted conditions so their presence is a good indicator of water pollution
What is an adaptation?
A feature that an animal or plant will have to help them survive in their environment
What do all organisms need to do to survive?
Compete for resources
What do the adaptations of Arctic animals have to do?
Reduce heat loss
What are the 4 main adaptations that desert animals have and why?
Large surface area to volume ratio so that more body heat is lost
To lose less water, they produce concentrated urine and produce very little sweat (they do this by either tolerating big changes in temperature of living in cool areas)
Thin layers of body fat and a thin coat to help them lose body heat
They have a sandy colour to camouflage them to avoid predators or sneak up on prey
What are the 3 adaptations that desert plants have and why?
Small surface area to volume ratio to reduce water loss
Water storage tissues
Deep or extensive roots to absorb as much water as possible
What are the 3 resources that animals need?
Space (territory), food and water
What are the 4 resources that plants need?
Light, space, water and nutrients
What do desert animals have to be adapted to do?
To save water and keep cool
What 3 adaptations can plants and animals have to deter predators?
Armour (eg. roses have thorns)
Poisons (like bees)
Warning colours (like wasps)
What are the 4 ways to measure environmental change with non-living indicators?
Satellites measure temperature of sea surface and the amount of snow and ice cover
Automatic weather stations contain sensitive thermometers that tell us atmospheric temperature change
Rain gauges tell us average rainfall
Dissolved oxygen meters tell us the concentration of oxygen in water
What do desert plants have to adapt to do?
Obtain water where there is little of it
What are the 3 non-living factors that can change an environment that plants and animals live in?
Change in average temperature
Change in average rainfall
Change in level of air or water pollution
What has other use have we found that stains are useful for?
They lower blood cholesterol and risk of heart disease in diabetic patients