Consider the following organisms :
birds,Mushroom,Crow,grass,Tiger,Vulture,frog,toadstool,Ape,Insects,Deer
Which of these organisms :
can form a three step food chain which occurs in the forest?

Answer

To determine which organisms can form a three-step food chain in a forest, we need to understand the relationships between these organisms in terms of who eats whom. A food chain typically consists of a producer, a primary consumer, and a secondary consumer.

### Step-by-step Solution:

1. **Identify Producers**:
- In a forest ecosystem, plants are the primary producers. From the given list, **grass** is the only producer.

2. **Identify Primary Consumers**:
- Primary consumers are herbivores that eat producers. From the list, **deer** is a primary consumer that eats grass.

3. **Identify Secondary Consumers**:
- Secondary consumers are carnivores that eat primary consumers. From the list, **tiger** is a carnivore that eats deer.

4. **Construct the Food Chain**:
- Based on the identified organisms, we can construct the following three-step food chain:
- **Grass (Producer) → Deer (Primary Consumer) → Tiger (Secondary Consumer)**

5. **Conclusion**:
- The three-step food chain formed is: Grass → Deer → Tiger.

### Final Answer:
The three-step food chain that occurs in the forest is: **Grass → Deer → Tiger**.

---