Answer:
The experiment should have more different subject groups, with each group consuming a different amount of beta carotene.
Explanation:
When designing an experiment, to determine the effect of the amount of a substance, the experimental design should be done to accommodate more than two experimental group with each group treated with different amount of the substance and also a control group. This will enable the researcher to determine the effect of the different ranges of amount.
In the example, in other to determine if vitamin A is dependent of the amount of beta carotene consumed, there should be more different subject groups, with each group consuming a different amount of beta carotene. 
 
        
                    
             
        
        
        
Answer:
The tympanic membrane and stapes of the bullfrog can be driven by airborne sound over a wide frequency range, with a broad maximum in their velocity amplitudes between 0.4 and 2 kHz (Mason and Narins, 2002a).
 
        
                    
             
        
        
        
The action that will directly affect the gravitational force between two objects is increasing the pressure on the objects (option B). 
<h3>What is gravitational force?</h3>
Gravitational force is a very long-range, but relatively weak fundamental force of attraction that acts between all particles that have mass; believed to be mediated by gravitons. 
Gravitational force can also be referred to as the force due to gravity of a planet. 
The gravitational force between two objects can be affected by the following factors:
- Increase in pressure
- Increase in temperature
- Increase in speed of objects
Therefore, the action that will directly affect the gravitational force between two objects is increasing the pressure on the objects.
Learn more about gravitational force at: brainly.com/question/12528243
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Answer:
Asexual reproduction is a mode of reproduction in which only one parent is involved to reproduce offspring. In asexual reproduction,the offsprings produced are exact copies of their parents. It is generally observed in very small sized organisms. Binary fission, Budding, Fragmentation etc.
Explanation:
 
        
             
        
        
        
Answer:
the vaccine causes the immune system to produce antibodies to the virus that causes the measles