Study the given data and answer the questions that follow.
A sample of an enzyme called lactase was isolated from the intestinal lining of a calf. Assays were undertaken to evaluate the activity of the enzyme sample.
The substrate of lactase is the disaccharide lactose. Lactase breaks a lactose molecule in two, producing a glucose molecule and a galactose molecule.
Two assays were carried out.
`{:("Lactose concentration (% w/v)",15,15,15,15,15,15),("Concentration of enzyme smaple (%v/v)",0,5,10,15,20,25),("Reaction rate "mu"mole glucose "sec^(-1)mL^(-1),0,25,50,75,100,125):}`
`{:("Lactose concentration (% w/v)",0,5,10,15,25,30),("Concentration of enzyme smaple (%v/v)",5,5,5,5,5,5),("Reaction rate "mu"mole glucose "sec^(-1)mL^(-1),0,15,25,35,40,40):}`
What are the variables in each of the two assays ?

Options

A. `{:(" ""Assay"1," ""Assay"2),("Lactose concentration", "Conentration of enzyme sample"):}
B. `{:(" ""Assay"1," ""Assay"2),("Concentration of enzyme sample", "Lactose concentration"):}`
C. `{:(" ""Assay"1," ""Assay"2),("Lactose concentration", "Lactose concentration"):}`
D. `{:(" ""Assay"1," ""Assay"2),("Conentration of enzyme sample", "Conentration of enzyme sample"):}`

Answer

To answer the question, we need to identify the variables in each of the two assays conducted to evaluate the activity of the enzyme lactase.

### Step-by-Step Solution:

1. **Identify the Assays**: We have two assays based on the data provided.
- **Assay 1**: The concentration of lactose is kept constant while varying the concentration of the enzyme sample.
- **Assay 2**: The concentration of the enzyme sample is kept constant while varying the concentration of lactose.

2. **Assay 1 Variables**:
- **Independent Variable**: Concentration of enzyme sample (% v/v) - This is the variable that is changed to observe its effect on the reaction rate.
- **Dependent Variable**: Reaction rate (µmole glucose sec^(-1) mL^(-1)) - This is the variable that is measured to see how it responds to changes in the enzyme concentration.
- **Controlled Variable**: Lactose concentration (% w/v) - This is kept constant throughout the assay.

3. **Assay 2 Variables**:
- **Independent Variable**: Lactose concentration (% w/v) - This is the variable that is changed to observe its effect on the reaction rate.
- **Dependent Variable**: Reaction rate (µmole glucose sec^(-1) mL^(-1)) - This is the variable that is measured to see how it responds to changes in the lactose concentration.
- **Controlled Variable**: Concentration of enzyme sample (% v/v) - This is kept constant throughout the assay.

4. **Conclusion**:
- In **Assay 1**, the variables are:
- Independent: Concentration of enzyme sample (% v/v)
- Dependent: Reaction rate (µmole glucose sec^(-1) mL^(-1))
- In **Assay 2**, the variables are:
- Independent: Lactose concentration (% w/v)
- Dependent: Reaction rate (µmole glucose sec^(-1) mL^(-1))

### Final Answer:
- **Assay 1 Variables**: Independent - Concentration of enzyme sample (% v/v); Dependent - Reaction rate (µmole glucose sec^(-1) mL^(-1)).
- **Assay 2 Variables**: Independent - Lactose concentration (% w/v); Dependent - Reaction rate (µmole glucose sec^(-1) mL^(-1)).