It’s estimated that by 2050, our population will reach 9.8 billion which is 1.6 billion more than the current population. By then, the areas that are currently used for agriculture will soon be dry due to lack of rain. In today’s lecture, I’d like to introduce two types of plants: succulents and annuals. They are expected to solve the anticipated lack of food.

Succulents are plants that store water in leaves, stems, and roots. They adapt to dry climates or soil conditions. Cacti are the most famous succulents. In general, plants lose water when they breathe through their leaves, so the bigger the surface area of their leaves, the bigger amount of water turns into steam. Cacti minimize the use of their leaves and breathe through their stems instead. Also, these plants breathe only at night to store water.

Annuals are plants that can complete their full life cycle in one growing season. Many annual plants grow from seeds, complete their life cycle quickly during the rainy season, and survive in the form of seeds in the following dry season. These plants are not affected by extreme dry conditions. Annual plants are common in semi-dry places where rainy season is of short duration.

What I have shown you may solve the possibility of food shortage in the coming years. However, we still need to look at it from different angles. Furthermore, the natural phenomena that took place in the past 40 million years could serve as an implication on how we can survive in the future.

The professor is talking about population increase and the anticipated lack of food. By then, the areas that are currently used for agriculture will soon be dry due to lack of rain. According to the professor, there are plants which are expected to solve the anticipated lack of food. The professor introduces two types of plants: succulents and annuals.

First, the professor gives an explanation about succulents that can adapt to dry climates or soil conditions. They store water in leaves, stems, and roots. Also, the professor introduces cacti as an example of a succulent and explains how they store water.

Second, the professor gives an explanation of the annuals that can complete their full life cycle in one growing season. The professor also introduces annuals as an example of plants that are common in semi-dry places where the rainy season is of short duration because they are unaffected by extreme dry conditions.

In this short lecture, I learned that succulents and annuals are unusual plants that can live in dry or semi-dry climates.

Have you ever paid attention to natural materials, the materials that can be found in plants, insects, and animals? What comes to your mind when you hear natural materials? Maybe you’re thinking of cotton, silk, and leather. These are correct, but today I’ll introduce the two strongest natural materials. The first strongest material is from plants, and the other one is from insects.

The first material is a nanofiber called nanocrystalline cellulose. It can be found in sequoia trees. A sequoia tree is usually 80 meters tall. It can carry hundreds of tons of weight and can live for 400 to 1,300 years. It is said that the nanocrystalline cellulose can bear 10 times more weight than steel. We can make strong shirts and gloves when we mix this strong material with an existing one.

In insects, cat fleas have the strongest materials in their body. It is an elastomeric protein called resilin. Resilin is a rubber-like protein and is the most flexible one in the world. When this rubber is squeezed or stretched, it will lose almost no energy. The flexible nature of resilin enables cat fleas to jump 100 times higher than their height.

If we extract these two materials’ DNA, we can create the strongest material. It can be used in cell phone cases, protective clothes, and sportswear. However, the reason why we focus on these materials is that they can improve medical items like artificial bones or artificial internal organs. Studying these materials can give people better options.

The professor is talking about materials in nature. According to the professor, these materials can be found in plants, insects, and animals. The professor introduces 2 materials as examples of materials in nature. One is nanocrystalline cellulose and the other one is resilin.

First, the professor explains that nanocrystalline cellulose is a strong material from plants. Also, the professor mentions how we can benefit from this material.

Second, the professor explains that resilin is a strong material from insects. The professor explained why cat fleas can jump high.

Through this lecture, I learned that nanocrystalline cellulose and resilin are strong materials that can be found in nature and they could improve our daily lives.

More than 50 million people die worldwide due to diseases that are left undetected. There are various medical screening tests available. Do you know people’s health could be revealed by breath analyzers? The human breath is composed of hundreds of components, which are called volatile compounds. These components are released every time a person exhales. By doing breath analysis using sensors, these volatile organic compounds in people’s breath could be analyzed to detect certain diseases in their early stages.

The technological advancement of breath analyzers has two major benefits. First, the breath analyzer could be integrated into a small handheld device, which could be used to test people in various settings in a noninvasive and simple way. So, a visit to the doctor would not be required. An example of this is the alcohol breath tester, which is being used by police officers to check the level of alcohol in a person’s breath. It could be used anytime and anywhere.

Second, the breath analyzer could be used to screen for many diseases at the same time. For example, cancer and diabetes could be detected at the same time instead of doing two different tests, which are usually more expensive and require more screening time, which makes diseases worse.

The average human body is composed of 55 to 60% water, which regulates body temperature, lubricates the joints, and nourishes the brain. People lose two to three liters of water every day through normal body functions such as breathing, urinating, bowel movements, and sweating, so it is important for the human body to compensate for the lost fluid. Maintaining a balanced water level in the body is important. Drinking eight glasses of water a day is the conventional way, according to experts. But do you know that drinking a very small amount or too much water could harm the human body?

If the water level in a human body is not balanced, it could lead to two conditions. First, let us talk about dehydration, which means low water levels in the human body caused by not enough consumption of fluids. The human body could detect this through the brain’s hypothalamus, where the sensory receptors signal the release of anti-diuretic hormones. Once the hormones reach the kidneys, they are triggered to retain more water, which causes dark and concentrated urine. Some examples of the physical effects of dehydration are a drop in skin moisture and signs of cognitive impairment.

The second condition is called overhydration, which is caused by consuming too much water in a very short time. The brain being overhydrated slows down or even stops the release of anti-diuretic hormones into the blood, which causes cells to swell. Some examples of the physical effects caused by overhydration are vomiting and headaches, which happen during water intoxication.

Have you ever wondered why our voices change as we grow older? Over the years, a human body undergoes a lot of changes. One of them is the depth of voice. There are two reasons as to why human voice changes over time: the age of vocal cords and the size of the larynx. The larynx or the voice box is a part of the respiratory system that is used to breathe, talk, and swallow. It is a system of different muscles that supports and moves the vocal cords inside it.

The age of a human’s vocal cords causes big changes. As a person ages, vocal cords ages too. People experience the first major shift in their voices when they are starting to become an adult. That’s the time when people’s voices start to deepen. That is a sign that the vocal cords are aging. Most people’s voices stay almost the same for about 50 years after the start of becoming an adult. However, as people grow older, they experience signs relating to an aging voice called presbyphonia.

Next is the size of the larynx. The voice is produced through the sound waves of the vocal cords. The bigger the vocal cords are, the deeper the voice is. Men have bigger larynges than women. This is the reason why men’s voices are bigger and deeper than that of women’s. When larynges and vocal cords grow, they create bigger sound waves which make people’s voices bigger and deeper as they age.

Are you aware of the autonomic nervous system? It is the part of the nervous system that works autonomously and controls certain body processes like blood pressure, pulse rate, and breathing. In this lesson, we will discuss the two main divisions of the autonomic nervous system which are the sympathetic and parasympathetic divisions.

Let’s start with the sympathetic division. This division prepares the body for stress and emergency situations. It automatically controls the body’s response to any noticed threats. This division is associated with the fight or flight response. The fight or flight response represent the options that people have when they are in danger. The options are dealing with the threat (fight) or running away to safety (flight). When someone is frightened, the person’s heartbeat accelerates and the breathing becomes faster. This is to provide enough energy and oxygen to the body as it responds to danger.

Next is the parasympathetic division. This division keeps the body at rest and it is responsible for storing and conserving the body’s energy not for immediate but for future use. It slows down the pulse rate and starts the digestion. This division is associated with the rest and digest function. The rest and digest function represent the time when the blood pressure decreases, the pulse rate slows down and the digestion starts as the body is at rest. It controls the body processes during ordinary situations. For example, wanting to relax on a weekend while watching your favorite television show on a comfortable chair calls for the rest and digest function.