Humans and artificial selection

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Artificial Selection

Artificial selection occurs when humans select which plants or animals to breed to pass on specific traits to the next generation.
Two organisms with desirable traits are crossed to produce offspring with those same traits.
By selecting and crossing individuals with desired traits for several generations, scientists increase the chance that offspring will have those traits.
Artificial selection is used in farming and ranching, such as breeding cows that produce the most milk to increase milk quality and quantity.
Plants are also selectively bred to increase size, flavor, and production; almost every fruit or vegetable has been improved by artificial breeding.
Example: generations of farmers have harvested corn with the largest kernels to produce today's corn.

Ears of teosinte (left), a teosinte-maize F1 hybrid (center), and modern corn (right) on the same scale, showing how generations of selective breeding for larger, more exposed kernels turned wild teosinte into today's corn.

Genetic Modification

Genetic engineering is a research field that aims to change the genetics of living organisms to have more desirable traits.
This technology has led to less crop damage and increased farm production, allowing farmers to produce more food on less land.
Crops have been engineered to produce better tasting food with a longer shelf life.
Genetic engineering also benefits medicine; for example, scientists have engineered bacteria to produce human insulin.
The human insulin gene is inserted into bacteria, which then produce human insulin as they reproduce, helping people with diabetes.

Cloning

A clone is an exact genetic duplicate of a living organism, like an identical twin but born at different times.
Cloning involves inserting DNA from one organism into an empty egg cell from another, tricking it to grow as if fertilized.
Clones must grow, develop, and learn like any other living thing; they cannot be produced instantly by a machine.
Even though clones have identical DNA, trait expression is subject to environmental influences.

Dolly the sheep, born in 1996 — the first mammal cloned from an adult body cell.

Gene Therapy

Gene therapy is the insertion of genes into a person's cells to cure a genetic disorder.
It only works for disorders caused by faulty genes, not diseases caused by viruses like AIDS.
Gene therapy uses a vector (carrier molecule), often modified viral DNA with viral genes removed, to incorporate the desired gene into patient's DNA.
The virus used in gene therapy is deactivated and not harmful to the human body.
Gene therapy is still experimental for diseases like hemophilia and cystic fibrosis, but may become common in the future.

Engineering Design

This standard involves engineering design to solve problems related to inheritance of desired traits.
The goal is to obtain, evaluate, and communicate information about technologies that change how humans affect inheritance.
Examples include artificial selection, genetic modification, animal husbandry, and gene therapy.
Analyze data from tests or simulations to determine the best solution for cultivating selected desired traits in organisms.

Inherited Differences and Benefits

Inherited differences among individuals in a population give some individuals a benefit.
Artificial selection takes advantage of these differences by selecting individuals with beneficial traits for breeding.
This process can lead to populations with enhanced traits over generations.
Understanding these differences is key to successful selective breeding and genetic modification.

Diapos

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1.What is artificial selection?
Easy
- AThe process by which humans select which plants or animals to breed in order to pass on specific traits to the next generation
- BThe process by which nature selects which organisms survive and reproduce
- CThe process of cloning an organism to produce an exact genetic duplicate
- DThe process of inserting genes into a person's cells to cure a genetic disorder
2.Which of the following is an example of artificial selection?
Easy
- ABreeding cows that produce the most milk
- BA cheetah being faster due to natural selection
- CA plant growing towards sunlight
- DA person developing immunity after a vaccine
3.Which of the following are examples of technologies that have changed the way humans affect the inheritance of desired traits in organisms? (select all that apply)
Easy
- AArtificial selection
- BGenetic modification
- CNatural selection
- DAnimal husbandry
- EGene therapy
4.Match each term with its correct definition.
Medium
- Artificial selection
- Genetic modification
- Cloning
- Gene therapy
- Humans select which organisms to breed for desired traits
- Changing the genetics of an organism to have more desirable traits
- Producing an exact genetic duplicate of an organism
- Inserting genes into a person's cells to cure a genetic disorder
5.Artificial selection and natural selection are the same process.
Easy
True or false?
6.Put the steps of artificial selection in the correct order.
Medium
- Select individuals with the desired traits
- Breed the selected individuals
- Repeat for several generations
- Identify the desired traits
7.Gene therapy can be used to cure diseases caused by viruses, such as AIDS.
Medium
True or false?
8.Clones have identical DNA, so their traits are completely unaffected by the environment.
Medium
True or false?

Plus de questions

9.In the context of artificial selection, what is the purpose of keeping careful records?
Medium
- ATo identify which traits are being passed on and make future breeding decisions
- BTo ensure all offspring are identical
- CTo prevent any genetic changes from occurring
- DTo compare artificial selection to natural selection
10.Almost every fruit or vegetable you eat has been improved by artificial selection.
Easy
True or false?
11.Put the steps for producing human insulin using bacteria in the correct order.
Medium
- Insert the human insulin gene into bacteria
- Bacteria reproduce and produce human insulin
- Harvest insulin from the bacteria
- Use insulin in patients with diabetes
12.Which of the following are possible benefits of genetic modification of crops? (Select all that apply)
Medium
- ALess crop damage
- BIncreased farm production
- CBetter tasting food
- DLonger shelf life
- EDecreased need for water
13.A farmer wants to breed cattle that produce more milk. She selects the cows that produce the most milk and only breeds those cows with the bulls from high-producing lines. After several generations, the average milk production increases. This is an example of which process?
Medium
- ANatural selection
- BArtificial selection
- CGenetic modification
- DGene therapy
14.Which of the following is an example of animal husbandry?
Easy
- ABreeding cows that produce the most milk
- BInserting a gene into bacteria to produce insulin
- CCloning a sheep
- DUsing a virus to deliver a gene to a patient
15.In artificial selection, the traits selected for are always beneficial to the organism in its natural environment.
Easy
True or false?
16.A scientist is studying a population of plants. She notices that some plants have larger seeds than others. She wants to increase the average seed size in the next generation. Which approach is most directly an example of artificial selection?
Medium
- ACross-pollinate only the plants with the largest seeds
- BExpose the plants to radiation to cause mutations
- CInsert a gene for large seeds into all plants
- DGrow the plants in soil with extra fertilizer
17.Which of the following are potential unintended consequences of artificial selection? (Select all that apply)
Hard
- AReduction in genetic diversity
- BIncreased susceptibility to diseases
- CImproved crop yields
- DLoss of traits that are not selected for
- EIncreased resistance to pests
18.A plant breeder wants to develop a variety of wheat that is resistant to a particular fungus. She crosses two wheat plants that show some resistance, then selects the offspring with the highest resistance to breed for the next generation. After several generations, she obtains a wheat variety with strong resistance. This is an example of:
Medium
- AGenetic modification
- BArtificial selection
- CGene therapy
- DCloning
19.A scientist wants to produce a new variety of tomato with a longer shelf life. Which of the following is the most direct use of genetic engineering to achieve this?
Medium
- ASelecting and breeding tomato plants that naturally have longer shelf life over many generations
- BInserting a gene from another organism that extends shelf life into tomato cells
- CCrossing two tomato plants and hoping for a mutation that gives longer shelf life
- DExposing tomato plants to radiation to cause random mutations
20.A farmer is using artificial selection to increase milk production in his herd. Which of the following practices are consistent with artificial selection? (Select all that apply)
Hard
- ABreeding only the cows that produce the most milk
- BKeeping detailed records of milk production and lineage
- CInjecting cows with hormones to increase milk production
- DAvoiding breeding cows that produce low amounts of milk
- ECloning the highest-producing cow and using the clone for breeding
21.Gene therapy can be used to cure diseases caused by faulty genes, such as hemophilia and cystic fibrosis.
Easy
True or false?
22.What is a clone?
Easy
- AAn exact genetic duplicate of a living organism
- BAn organism produced by artificial selection
- CAn organism with genes from two different species
- DAn organism that has been genetically modified
23.Put the steps for cloning a sheep in the correct order.
Medium
- Insert DNA from a cell of one female into an empty egg cell from another female
- The cell grows and develops inside the host mother's womb
- The cell is tricked into thinking it has been fertilized
- A clone is born
24.A farmer keeps records of milk production for each cow in her herd over several years. She notices that the cows with the highest milk production tend to have daughters with higher milk production than average. Based on this data, which conclusion is best supported?
Medium
- AMilk production is entirely determined by the environment.
- BMilk production has a genetic component that can be passed to offspring.
- CThe farmer's record keeping has no effect on the herd.
- DAll cows in the herd have identical genetics for milk production.
25.Complete the sentence.
Easy
Artificial selection occurs when humans select which plants or animals to breed in order to pass on ____ traits to the next generation.
26.Approximately how many generations of selective breeding could it take to produce dogs with a desired set of traits?
Medium
27.Complete the sentence about cloning.
Medium
A clone is an exact genetic ____ of a living organism, like an identical twin, but born at different times.
28.Complete the sentence about the purpose of insulin in the body.
Easy
Insulin helps to remove ____ from the bloodstream and put it in cells where it can be used by the mitochondria to produce energy.
29.Complete the sentence about gene therapy vectors.
Medium
In gene therapy, the vector is usually modified ____ DNA from which the viral genes have been removed.
30.Complete the sentence about how humans have changed corn.
Medium
Generations of farmers have harvested corn with the largest ____ to produce the corn we have today.
31.Explain why gene therapy cannot be used to cure diseases like AIDS, and give an example of a disorder it might be used to treat.
Hard
32.Describe the steps a scientist would take to produce human insulin using bacteria, and explain why the bacteria are able to produce human insulin.
Hard
33.Selective breeding could produce dogs with a desired set of traits in about how many generations?
Medium
- A12 generations
- B11 generations
- C14 generations
- D13 generations
34.The diagram compares teosinte, the wild ancestor of corn, with modern corn. Based on the diagram, which statement describes how these two traits changed as humans bred teosinte into modern corn?
Medium
- AThe number of branches and the number of flowers both increased.
- BThe number of branches increased, but the amount of edible food decreased.
- CThe number of branches decreased, but the amount of edible food increased.
- DThe number of flowers decreased, but the number of branches increased.
35.A scientist inserts a piece of a bacterium's DNA into the DNA of a corn plant so the corn will produce a trait the bacterium has, such as resistance to insect pests. This direct change to the corn plant's genetic material is an example of:
Medium
- Anatural selection
- Banimal husbandry
- Cgene therapy
- Dgenetic modification
36.Coat color and other traits in horses are often artificially selected when horses are bred. Describe one advantage and one disadvantage of selecting traits artificially in horses.
Medium

Notes de révision

## Humans and Artificial Selection Artificial selection (selective breeding) is when humans choose which plants or animals to breed together to get desired traits. This changes the traits of a population over time. - **Process**: Humans select individuals with desirable characteristics (e.g., larger seeds, better wool) and breed them. Offspring inherit those traits. Over generations, the population changes. - **Examples**: Dogs, cats, cattle, wheat, rice, maize. Maize was bred from teosinte. Robert Bakewell improved sheep (New Leicester) and cattle (Dishley Longhorn) in the 1700s, doubling bull weight from 370 to 840 pounds. - **Unintentional selection**: Sometimes traits change due to human practices (e.g., ploughing) without deliberate breeding. - **Key terms**: Breeds (animals), varieties/cultivars (plants), crossbreed/hybrid (offspring of different breeds). - **Darwin**: Used artificial selection as an analogy for natural selection. He wrote: "if feeble man can do much by his powers of artificial selection, I can see no limit to the amount of change... which may be effected... by nature's power of selection." - **Technologies**: Inbreeding, linebreeding, outcrossing are methods used in animal breeding. **Important**: Artificial selection is directed by humans; natural selection is non‑directed.

Artificial selection: The process by which humans breed plants or animals for specific phenotypic traits by choosing which individuals reproduce.
Selective breeding: Another name for artificial selection; humans select which individuals to breed to produce desired traits.
Breed: A group of domesticated animals with similar characteristics, produced by selective breeding.
Variety / Cultivar: A type of domesticated plant developed by selective breeding.
Crossbreed / Hybrid: Offspring from two different breeds (animals) or varieties (plants).
Inbreeding: Breeding between closely related individuals to maintain desired traits.
Linebreeding: A form of inbreeding that keeps offspring related to a particular ancestor.
Outcrossing: Breeding between unrelated individuals to introduce new traits.

Cartes mémo

What is selective breeding?

Selective breeding (artificial selection) is the process by which humans choose which animals or plants to reproduce to develop specific traits.

What is another name for selective breeding?

Artificial selection.

What are domesticated animals called in selective breeding?

Breeds.

What are domesticated plants called in selective breeding?

Varieties, cultigens, cultivars, or breeds.

What is a crossbreed?

A crossbreed is the offspring of two purebred animals of different breeds. In plants, crossbred plants are called hybrids.

Who discussed selective breeding in On the Origin of Species?

Charles Darwin.

How did Darwin use artificial selection in his theory?

Darwin used artificial selection as an analogy to explain natural selection, but noted that natural selection is non-directed.

Can selective breeding be unintentional?

Yes, selective breeding can be unintentional, for example, when farming practices inadvertently favor certain traits.

Give an example of unintentional selective breeding.

In some grains, an increase in seed size may have resulted from certain ploughing practices rather than intentional selection.

Since when has selective breeding been practiced?

Since prehistory.

Name a crop that required large changes from its wild form through selective breeding.

Maize (corn), which was selectively bred from teosinte in Mesoamerica.

Who established selective breeding as a scientific practice in the 18th century?

Robert Bakewell during the British Agricultural Revolution.

What sheep breed did Robert Bakewell improve?

The Lincoln Longwool, which he used to develop the New Leicester (Dishley Leicester) sheep.

What characteristics did Bakewell select for in sheep?

Large, fine-boned sheep with long, lustrous wool.

How did Bakewell change cattle breeding?

He was the first to breed cattle primarily for beef, creating the Dishley Longhorn.

How did the average weight of bulls change from 1700 to 1786 due to selective breeding?

It increased from 370 pounds (168 kg) to 840 pounds (381 kg).

What horse breed did Bakewell develop?

The Improved Black Cart horse, later known as the Shire horse.

What term did Charles Darwin coin for selective breeding?

Selective breeding (he used 'artificial selection' in his book).

What is the difference between artificial selection and natural selection?

Artificial selection is directed by humans to produce desired traits, while natural selection is non-directed and driven by environmental pressures.

Name two techniques used in animal breeding alongside artificial selection.

Inbreeding, linebreeding, and outcrossing (any two).

What is the purpose of selective breeding in agriculture?

To develop plants and animals with desirable traits such as higher yield, disease resistance, or specific physical characteristics.

How did ancient Romans contribute to selective breeding?

They practiced selective breeding and wrote treatises advising on selecting animals for different purposes.

What did the 11th-century scholar Abu Rayhan Biruni write about selective breeding?

He noted the idea in his book India, giving examples like farmers selecting corn and beekeepers culling unproductive bees.

What is the modern breed that descended from Bakewell's New Leicester sheep?

The English Leicester (or Leicester Longwool), primarily kept for wool production.

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