Wind energy describes the energy stored in moving air that can be harnessed for electricity. When air moves, it has kinetic energy, and turbines capture that energy as the blades spin, turning it into electrical energy through a generator. Geothermal energy is heat from beneath the Earth’s surface, uranium is a nuclear fuel used to produce heat in reactors, and chlorofluorocarbons are chemicals with no direct role in generating electricity. Wind energy is the term that fits the idea of using moving air to produce power.

Gas exchange between the body and the environment is performed by the respiratory system. It starts with the nose, which filters and warms or humidifies incoming air, then the air moves down the trachea into the lungs. In the lungs, tiny air sacs called alveoli sit next to a network of capillaries, and this is where the exchange happens. Oxygen moves from the air in the alveoli into the blood, while carbon dioxide moves from the blood into the alveoli to be exhaled. This exchange relies on differences in partial pressures and occurs across a very thin alveolar membrane. The circulatory system is essential for transporting these gases to and from tissues, but the actual transfer of gases occurs in the lungs. The digestive system handles nutrients from food, and the nervous system coordinates and controls body functions.

During mitosis, the goal is to distribute an identical set of chromosomes to each daughter cell. The DNA is replicated in S phase, so there are two sister chromatids per chromosome, but when mitosis proceeds, those chromatids are separated so that each daughter cell receives one copy of every chromosome. After cytokinesis, both daughters have the same number of chromosomes as the parent cell (for a diploid organism like humans, 46 in somatic cells). So the chromosome count is preserved across division, even though the DNA content was briefly doubled during replication. This is different from meiosis, where the chromosome number is halved to produce gametes.

A histogram shows how a dataset is distributed across value ranges. Data are grouped into consecutive intervals (bins), and the height of each bar represents how many observations fall into that range. This lets you see the overall shape of the data: where values cluster, whether the distribution is symmetric or skewed, if there are multiple peaks, and whether there are outliers at the extremes. It focuses on a single variable’s distribution, unlike plots that reveal relationships between two variables or trends over time.