Biology 1 Flashcards
What is an environment
An organism’s surroundings are its environment.
What can environmental factors do?
In all environments there are environmental factors that can change the organism, and non-living factors such as temperature or the amount of light.
What are the features of an organism
The features of an organism are its characteristics.
What are physical environmental factors?
Physical environmental factors are non-living factors.
What is variation?
The differences between the characteristics of organisms are known as variation.
What is environmental variation?
Environmental variation is variation caused by an organism’s environment.
What are some examples of environmental variation?
In humans, examples of environmental variation include scars and hairstyles.
Scars are made by
physical environmental factors, such as fire or sharp objects.
Hairstyles are caused by
Hairstyles follow fashion, which is an environmental factor caused by other people in your environment.
What is continuous variation?
Variation that can have any value between two points is continuous variation.
What is discontinuous variation?
Variation that can only have a value from a limited set of possible values is discontinuous variation.
What is classification
Classification is sorting organisms into groups.
What is a species?
A species is indeed the smallest group an organism can be classified into. A species is a group of organisms that share similar characteristics and can interbreed to produce fertile offspring. This means that individuals within a species can mate and create viable offspring that can also reproduce.
What do offspring get when they are born?
Offspring get a mixture of characteristics from their parents.
What is another way of saying “getting characteristics from their parents”?
We say they inherit these characteristics.
What is inherited variation?
inherited variation be characteristics which are inherited by their parents where it is transferred as a mixture between the two to its offspring.
Examples of inherited variation
Human eye colour, dimpled chins and blood groups.
Where are the instructions for inherited characteristics?
The instructions for inherited characteristics are stored in the genetic information found inside the nuclei of cells.
What happens in sexual reproduction?
In sexual reproduction, two gametes (one male and one female) fuse during fertilization to produce a zygote. Since the zygote contains genetic information from two parents, the offspring will have some characteristics of each parent.
What does every gamete contain?
Every gamete contains slightly different genetic information; no two gametes are identical.
Give an example of differences of gametes
For example, in people with dimpled chins, some of their gametes carry the instructions for a dimpled chin and some of their gametes may not. Since all gametes are different, brothers and sisters do not look exactly the same.
An example of discontinous inherited variation?
One example of discontinous inherited variation is blood group.
2 more examples of discontinous variation?
Having a dimpled chin and being able to roll your tongue.
Tell me 2 examples of contiuous inherited variation?
Human height and skin colour.
Explain how height variation can also be environmental
However, like many characteristics, these can also be affected by environmental factors. For example, tall parents are likely to produce tall children but children can only grow tall if they eat a healthy diet.
What do characteristics usually show when plotted on a histogram?
Characteristics that show continuous variation usually give a ‘bell shape’ when plotted on a bar chart. We can make this more obvious if we join the tops of the bars with a smooth curve.
What is the bell shape known as?
this shape is known as a normal distribution (and is the shape we often see in characteristics that show continuous variation)
What is statistics?
Statistics is collecting, analyzing and presenting data.
When do we use statistics:
Collect data (e.g using samples to estimate values)
Draw conclusions (e.g finding correlations using scatter graphs or calculating averages)
Present findings (e.g drawing graphs)
Make predictions
What is probability?
Probability is how likely something is going to happen
What did Watson and Crick do?
At lunchtime on 287 February 1653, two men burst into the eagle pub in Cambridge and one of them announced: ‘we have discovered the secret of life.’ Their names were James Watson and Francis Crick. They had just made a cardboard model of a substance called DNA.
Who did Watson and Crick show their model to?
Watson and Crick used their own and other scientists data to build their model. They showed their first attempt to Rosalind Franklin, who told them it was wrong.
Where is DNA found?
DNA is found in structures called chromosomes inside the nuclei of cells.
What does each chromosome contaim?
Each chromosome contains one enormously long DNA molecule.
What information does DNA contain?
It is DNA that stores genetic information, which controls inherited characteristics.
What are genes?
Genetic information is not stored in all parts of a DNA molecule but only in sections called genes. A few characteristics (such as the ABO blood group) are controlled by one gene. Most characteristics are controlled by many genes.
How many chromosomes does a human nucleus contain?
A human cell nucleus contains 46 chromosomes which contains genes.
How many chromosome pairs does our cells contain?
Most of your cells contain 23 pairs of chromosomes (46 in all).
What genes do both chromosomes in a pair contain?
Both chromosomes in a pair contain the same genes and are the same size, apart from the sex chromosomes.
What type of chromosomes do girls have?
Girls have two X sex chromosomes, which are the same size.
What type of chromosomes do boys have?
Boys have one X and one much smaller Y sex chromosome.
How many chromosomes do gametes contain?
Unlike body cells, gametes only contain 23 chromosomes.
What happens when the two gametes fuse?
The resulting zygote has 46 chromosomes.
What happens after a zygote is formed?
After a zygote has formed, cell division occurs over and over again, forming a ball of cells. Each of these cells contains identical copies of the same 46 chromosomes.
What happened 65 million years ago? How did the dinosaurs go extinct
75% of the Earth’s species became extinct, including the dinosaurs. Many scientists think that a giant meteorite hit the Earth, throwing so much dust into the atmosphere that it blocked out the sunlight. Evidence for this includes the remains of a 180km wide crater near Mexico, which was formed at this time.
What causes adaptation?
The adaptations of an organism are due to its genes.
Changes in an ecosystem can be bad for species because?
Changes in an ecosystem can affect species in an area because they may no longer be so well adapted to the new conditions.
What can make organisms endangered or extinct?
Changes in physical environmental factors
Competition from other organisms
Disease
Human activities (hunting, clearing habitats, using poisons)
Grey and red squirrels explained
Grey squirrels came to the UK, the native red squirrels are rare. The greys store more fat in their bodies, so if there is little food during a long winters, greys are more likely to survive while the reds may die. The greys are better adapted than the reds.
Explain the competition between the grey and the red squirrels
Greys and reds are in competition for food. Greys can digest unripe acorns but reds cannot, this allows the greys to eat the acorns before the reds which means the reds get less good. When food is limited, more of the better-fed greys survive and reproduce. The greys population increases faster, leaving even less food for the reds.
Biodiveristy
All the different types of species
Why should we preserve biodiversity?
Extinctions also upset ecosystems and change food webs. So, we need to preserve the biodiversity on Earth.
How can we preserve biodiversity?
- Banning the hunting of certain animals
- Setting nature reserves
- Breeding programmes
What are gene banks?
We can also store parts of organisms (e.g. seeds, gametes) that can be used to produce that organisms again if they become extinct. These materials are stored at low temperatures in gene banks.
Explain why pale butterflies became black during manchester 1850 to 1895?
During this time many factories were built and these churned out huge amounts of soot, turning buildings and trees black. Birds could easily spot the pale moths on the blackened buildings and treesm and so more pale ones were eaten. The black moths were harder to spot and so more of them survived and reproduced, and their numbers increased.
Explain why the pale butterfly story is natural selection and tell me the definition for it
This is an example of natural selection caused by a change in the environment. The environment is \selecting’ certain genetic variations in characteristics, which are passed on to the next generation.
This is an example of natural selection caused by a change in the environment. The environment is ‘selecting ‘ certain genetic variations in characteristics, which are passed on to the next generation.
Natural selection: the process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin, and it is now regarded as be the main process that brings about evolution.
Explain how natural selection allowed the Tilapia to stay at the Salton Sea
The only fish still living in the Salton sea are of a species called tilapia. They are usually found in fresh or slightly salty water. If tilapia from a freshwater lake are put into water from the Salton Sea, they die. The tilapia in the Salton Sea have become better adapted to more salty water. This gradual change in adaptation is due to natural selection. When the Salton Sea started getting salty, by chance some tilapia had genetic variations that allowed them to cope better with the salt. More of these fish survived than those that could not cope so well with the salt. So, more of the ‘salt-tolerant’ fish reproduced, and the next generation of tilapia therefore contained more of the ‘salt tolerant’ fish. As the sea got saltier, this process happened over and over again. Today all the Salton Sea tilapia fish can cope with very salty water.
What is evolution?
A change over time in the characteristics of organisms is known as evolution.
What did Charles Darwin and Alfred Russel Wallace create?
Both developed a hypothesis that natural selection causes evolution. This is now usually called ‘Darwin’s theory of evolution’.
Variation
Variation = variety or differences
organisms in different species are different because they contain different genetic information
a species contains organisms that share features and can reproduce with each other
there are differences between species
Species
A species is a group of organisms that can interbreed and produce fertile offspring and have similar characteristics.
5 kingdoms
Fungi protoctists prokaryotes plants
All organisms are __ into different groups
All organisms are classified into different groups
What are the biggest groups called
Kingdoms
What are the smallest groups called
Species
What graph do we use for continuous variation
we use a line graph or a histogram
What graph do we use for discontinuous variation?
We show discontinuous variation using a bar chart
What are and what makes up rungs?
Rungs join together the strands of the DNA. Each rung is made up of substances called ‘bases’. Each rung contains two bases, which ae joined together. We describe this as a ‘base pair’
What is DNA in simple terms
DNA, or deoxyribonucleic acid, is the genetic material that carries the instructions for the development, functioning, and reproduction of an organism. DNA is the molecule that controls what the cell does
DNA contains a code that gives the cell instructions for what to do
Why blend the kiwi - KWII
Blending the kiwi breaks down the cell walls exposing the cells membranes
Why use detergent - KWII
Detergent dissolves the fatty cell membranes
Why use salt - KWII
The salt makes the DNA stick together. The DNA doesn’t dissolve in alcohol so it coagulates to form a jelly-like substance that you can see.
What is an ecosystem?
All the organisms and physical environmental factors in an area form an ecosystem.
Which scientists found DNA?
James Watson, Francis Crick found the structure of DNA using other scientists’ data from Rosalind Franklin and Maurice Wilkins.
What does a chromosome contain
A chromosome contains a long molecule of DNA. Certain sections of that DNA molecule contain the genetic information and are called genes.
Why can organisms become extinct
Organisms become endangered or extinct when they are no longer adapted (suited) to their environment.
This can be because of:
changes in the environment
competition with other species
disease
human activities e.g. hunting,
clearing land
Lamarcks idea
Repeated use of a feature by
the organism will cause this feature
to develop during the life time of the
organism
These acquired, useful changes will be
passed on to the offspring
Charles Darwin Idea
A species will show variation
in their features as a result of the genes they inherit. This makes some members of the species more suitable to the environment i.e. they are better competitors.
This means they will survive and reach
breeding age, and pass on the genes
that made them suitable
