A model organism is a species that has been widely studied to understand a particular biological phenomena, normally used because they are easy to breed and maintain in a laboratory setting and has certain experimental advantage.
The criteria that Thomas hunt Morgan was looking for include; the model organism should be small in size, easy to keep in the laboratory and also able to produce large number of off springs in a short time.
The correct answer is letter A. Venom glands and varied diets are the reasons why cane toads are considered as invasive species in Australia. They cause major ecological imbalance within their immediate surroundings and have caused an infestation all over Australia.
Answer:
It is usually associated with physical growth delays, mild to moderate intellectual disability, and characteristic facial features. The average IQ of a young adult with Down syndrome is 50, equivalent to the mental ability of an eight- or nine-year-old child, but this can vary widely.
Symptoms: Delayed physical growth, characteristic facial features, mild to moderate i...
Other names: Down's syndrome, Down's, trisomy 21
Causes: Third copy of chromosome 21
Risk factors: Older age of mother, prior affected child
Explanation:
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The mantle is made of a solid rocky substance.