Sample Answer:
The lesson is about mutual symbiosis, which the reading passage defines as a kind of cooperative relationship between two distinctly different organisms. It can be between animals, plants, and even bacteria. The professor gives two examples illustrating mutual symbiosis. In his first example, bees gather nectar and pollen from flowers in order to meet their needs for food and to feed their hives. Bees travel from one flower to another seeking food; in doing so, they also carry pollen from one plant to another on the hairs of their legs. Flowering plants need pollen from other plants in order to reproduce; therefore, bees help the flowers pollinate and reproduce. The professor's second example also illustrates not only a mutually beneficial relationship but also that of a smaller organism, bacteria, living in a larger host, humans. The bacteria in human intestines get food from what the person ingests, and it helps with digestion and training the immune system, thus benefiting the host.
Transcript:
Now listen to part of a lecture on this topic.
M: Today, um, we are going to talk about mutual symbiotic relationships. Perhaps, the classic example of mutual symbiosis is that of bees and flowering plants. Bees travel from flower to flower in search of nectar and pollen. Back in their hives, the bees convert the energy-rich nectar and protein-rich pollen into food. With ample food supplies, the hive grows and flourishes.
OK, so, bees have dense hairs on their legs that are used to collect pollen. As they fly from flower to flower gathering food, they are also spreading the pollen from one flower to another. Now, um, flowers have both male and female reproductive apparatus, and in order for flowering plants to reproduce, one plant needs the pollen from another plant. And that's where the bees come in, inadvertently pollinating the plants, thus aiding in the plants' reproduction.
Sometimes, the relationship is that of a symbiote living literally within a host. Let's take an example close to home, really close. Inside each of our intestines are billions of microscopic bacteria. I'm not referring to the ones that make you sick, but rather the bacteria that aid in digestion. See, without these beneficial bacteria, we couldn't digest much of what we eat. Moreover, the bacteria also help train the immune system to better identify and respond to harmful bacteria.