How do biologist think that ancient green algae were the ancestors of today's plants?

Answer 1

The chloroplasts, probably. All green plants have tiny green things inside their cells called chloroplasts. This is where photosynthesis takes place. Like mitochondria, the chloroplasts also contain their own DNA. This can be decoded and compared to the chloroplasts of modern, land living plants.

Algae that tries to live on land faces many of the same problems animals like fish do, namely gravity and moisture. Plants solved both problems by developing a series of hollow tubes which ran through the plant's body. This was a way to move water around, since it could no onger simply soak into the plant all around it underwater. The tubes also could be reinforced, allowing the plant to grow upright. This was important because plants compete with one another for sunshine. The tallest plant gets the most sunshine. Reproduction of course was complicated by the lack of water. Algae reproduce with eggs and sperm which swim in the water. In air, plants first developed spores with moisture proof walls. The spores landed in a moist spot and germinated. Millions of years later, plants developed seeds. Unlike spores, seeds are complete plants in embryonic form. Spores are just single cells. Seed plants also deleloped pollen. This is equivalent to sprem, but can be dried out completely and carried either by the wind or by insects. Land plants formed many symbiotic relationships with animals in order to increase their reproductive success.

Answer 2

Biologists believe that ancient green algae were the ancestors of today's plants based on several lines of evidence. Green algae and plants share many similarities, including similar chloroplast structure, photosynthetic pigments, and cell wall composition. Additionally, genetic analysis has revealed genetic similarities between green algae and plants. These findings suggest that green algae gave rise to the first land plants through evolutionary processes.