<span>The discovery of thornless plants was made around the turn of the 20th century. To name one such thornless plant, particularly, the Blackberry plant, the deviation from the thorned blackberry canes were discovered in the United States. Since then, several different thornless blackberry varieties have been cultivated for fruit gardens.</span>
Explanation:
Karyotyping is <u>a test to examine chromosomes in a sample of cells</u>. This test can help identify genetic problems as the cause of a disorder or disease.

Answer:
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Explanation:
The book called "On the Origin of Species"
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Shadows are made by blocking light. Light rays travel from a source in straight lines. If an opaque (solid) object gets in the way, it stops light rays from traveling through it. This results in an area of darkness appearing behind the object. The dark area is called a shadow