5 Selective breeding Flashcards
What happened around 12 000 years ago?
The human way of life changed significantly.
What did humans begin to do?
Humans began to grow plants and keep animals for milk and meat. They became farmers rather than hunters.
What have humans tried to do ever since the cultivation of the first wheat and barley and the domestication of the first stock animal?
Humans have tried to obtain bigger yields from them.
How did they attempt to do this with plants?
They cross-bred different maize plants (and barley plants) to obtain strains that produced more grain.
How did they attempt to do this with animals?
They bred sheep and goats to give more milk and meat – selective breeding had begun.
What are animals and plants used for today?
Today, animals and plants are bred for more than just food. For example, animals are used to produce a range of medicines and for research into the action of drugs.
What is selective breeding?
It is the process where humans cross-
breed individual animals or plants that have been chosen because they show certain characteristics. Used to produce domestic animals and crop plants. Also known as artificial selection.
Why is it nicknamed artificial selection?
It is sometimes called ‘artificial selection’, as human choice, rather than environmental factors, is providing the selection pressure.
What does modern gene technology enable us to do in terms of selective breeding?
Modern gene technology makes it possible to create a new strain of plant within weeks, rather than years.
What has traditional selective breeding been used on?
- Plants.
- Animals.
How did farmers use traditional selective breeding on plants?
Traditionally, farmers have bred crop plants of all kinds to obtain increased
yields. Probably the earliest example of selective breeding was the cross-
breeding of strains of wild wheat.
What was this aim of selective breeding?
The aim was to produce wheat with a much increased yield of grain and with shorter, stronger stems.
Where was this wheat used?
This wheat was used to make bread.
What is an image that shows how modern wheat is the result of selective breeding by early farmers?
Is it only just wheat that has been used in selective breeding?
Other plants have been selectively bred for certain characteristics.
What is an example of another plant that has been selectively bred for certain characteristics?
One species of wild brassica (Brassica olera) was selectively bred to give several strains, each with specific features.
What is brassica?
Brassica is a genus of cabbage-like plants.
What were the characteristics of some of the brassica strains?
Some of the strains had large leaves, others had large flower heads, and others produced large buds.
What is a diagram which shows the process of selectively breeding the original wild brassica plants to enhance certain features and how it has produced several familiar vegetables?
What kind of vegetables have been produced by selective breeding?
Selective breeding has produced many familiar vegetables.
What are some examples of these vegetables?
Besides the ones produced from Brassica, selective breeding of wild Solanum plants has produced the many strains of potatoes that are eaten today. Carrots and parsnips are also the result of selective breeding programmes.
What type of strains are crop plants bred to produce?
- Give higher yields.
- Are resistant to certain diseases (the diseases would reduce the yields).
- Are resistant to certain insect pest damage (the damage would reduce the yield).
- Are hardier (so that they survive in harsher climates or are productive for
longer periods of the year). - Have a better balance of nutrients in the crop (for example, plants that
contain more of the types of amino acids needed by humans).
What is a diagram that shows a field of potato plants?
What is an explanation of this divide of the potato plants?
The plants on the right have been
bred to be resistant to a fungal pest. Plants on the left are not resistant to the pest.
