study the four statements (A-D) given below and select the two correct ones out of them
(A) Definition of biological soecies was given by Ernst mayr
(B) photoperiod does not affect reproduction in plants
© Binomial nomenclature system was given by Ernst Whittaker
(D) In unicellular organisms, reproduction is synonymous with growth
The two correct statments are

Options

A. a and b
B. b and c
C. c and d
D. a and d

Answer

To solve the question, we need to analyze each of the four statements (A-D) and determine which two are correct.

### Step-by-Step Solution:

1. **Analyze Statement A**:
- Statement A claims that the definition of biological species was given by Ernst Mayr.
- This statement is **true**. Ernst Mayr is indeed known for his definition of biological species, which emphasizes reproductive isolation and the ability to interbreed.

2. **Analyze Statement B**:
- Statement B states that photoperiod does not affect reproduction in plants.
- This statement is **false**. Photoperiod is a critical factor in regulating the reproductive cycles of many plants, influencing flowering and other reproductive processes.

3. **Analyze Statement C**:
- Statement C asserts that the binomial nomenclature system was given by Ernst Whittaker.
- This statement is **false**. The binomial nomenclature system was developed by Carl Linnaeus, while Ernst Whittaker is known for his five-kingdom classification system.

4. **Analyze Statement D**:
- Statement D claims that in unicellular organisms, reproduction is synonymous with growth.
- This statement is **true**. In unicellular organisms like amoeba, reproduction often occurs through a process that also involves growth, making these two processes closely linked.

### Conclusion:
From the analysis, the two correct statements are:
- **A**: Definition of biological species was given by Ernst Mayr.
- **D**: In unicellular organisms, reproduction is synonymous with growth.

Thus, the correct answer is **A and D**.