Plant Evolution

Step 1: Understand the role of the micropyle.
The micropyle is the small opening in the ovule where the pollen tube enters. It is the site through which the sperm cells travel to fertilize the egg cell in the embryo sac.
Step 2: Role of other components.
- Antipodal Cells: These are the cells located at the opposite end of the embryo sac and do not guide the pollen tube entry.
- Filiform apparatus: Found in synergid cells, it helps in guiding the pollen tube into the ovule but not directly related to the entry.
- Synergids: These cells help attract the pollen tube but don’t guide the entry. They play a significant role in fertilization once the pollen tube enters.
Step 3: Conclusion.
The micropyle directly guides the entry of the pollen tube into the embryo sac.
Final Answer:

Step 1: Understanding the groups of plants.
The order in which different plant groups appeared on earth is based on their evolutionary history.
- Angiosperms (A): These are the most recent group of plants, characterized by flowering plants that produce seeds enclosed within a fruit. They are the most diverse and abundant group of plants today.
- Seed ferns (B): These plants were among the first to produce seeds, but they are now extinct. They appeared before angiosperms and were present during the late Paleozoic era.
- Rhynia type plants (C): These are some of the earliest known vascular plants that appeared around 400 million years ago, during the Silurian period. They did not have true roots, leaves, or vascular tissue like modern plants.
- Psilophyton (D): These were some of the earliest land plants, appearing before Rhynia. They were simple, vascular plants with no roots or leaves, and they represent one of the first steps in plant evolution on land.
Step 2: Arranging the groups in order of appearance.
The groups of plants appeared in the following order:
- Psilophyton (D): One of the first plants to appear on land.
- Rhynia type plants (C): Appeared after Psilophyton, with more complex features like vascular tissues.
- Seed ferns (B): Followed the earlier plants, marking the appearance of seed-producing plants.
- Angiosperms (A): The last to appear, with the development of flowering plants.
Step 3: Conclusion.
The correct order of appearance from the earliest to the most recent is: (C), (D), (B), (A).
Final Answer:

Step 1: Understand the structure of the ovule.
The ovule of a plant has two ends: the micropyle and the chalaza. The micropyle is the end through which the pollen tube enters, while the chalaza is located opposite the micropyle.
Step 2: Identify the opposite of the micropyle.
The chalaza is the part opposite to the micropylary end of the ovule, and it is where the ovule attaches to the ovary wall.
Conclusion:
The correct answer is (2) Chalaza.
Final Answer: