Prokaryotes are unicellular organisms with no nuclear membrane-enclosed nucleus. These organisms are believed to be the origin of life and to have dominated the earth up to the Precambrian era. Prokaryotes, cells with a membrane-bound nucleus originate from eukaryotes and therefore have eukaryotes as their ancestors.

Theta waves are brain waves that occur just when you are asleep or dreaming. These waves do not occur during the deepest of sleep but occur during light phases or just before waking up. Theta waves are used in making memories and also for processing information. Theta waves are faster than delta waves but slower than alpha waves. They fall at the end of the spectrum and are measured in the 4 to 8Hz range.

The suprachiasmatic nucleus, also known as the SCN, is a bilateral structure found in the anterior region of the hypothalamus of the brain. It is the controller of the circadian timing system responsible for all the circadian rhythms of the body. The sleep-wake cycle is controlled and regulated by this structure.

Perennials are plants that will thrive for many growing seasons. A typical perennial has a life span of more than two years. These plants will survive any season and will persist year in year out. Most perennials are herbaceous and their shoot system tends to die every autumn and winter, leaving the root system intact. During spring and summer, the shoot grows again from the root and this process continues for a long time.

Synchondrosis is a type of cartilaginous joint where bones are completely joined together or united by hyaline cartilage. Synchondroses are immovable joints and are therefore described as synarthroses. Although also found in mature skeletal samples, synchondrosis is found mainly in developing. It is useful in providing early support for the skull during development.

Plants are autotrophs and this means they are capable of manufacturing their own food. This process is known as photosynthesis. In photosynthesis, CO2 is utilized by plants together with water in the presence of sunlight to produce glucose and oxygen gas. With this, plants tend to create in balance the amount of Carbon dioxide in the body. Animals on the other hand inhale oxygen from their environment and release carbon dioxide in return. This entire respiratory process of plants and animals helps in creating a balance between the CO2 and O2 levels in the atmosphere. Plants take in CO2 and will not release any thus maintaining a balance in the amount of CO2 in the environment.

The bioelectrical impedance machine is the most accurate medium of measurement used today in the measurement of body fat. This machine is very efficient as it helps in measuring the exact amount of body fat present without using the weight of the person.

Pulmonary circulation entails how blood is moved between the heart and the lungs. Deoxygenated blood is transported to the lungs so as to get them to absorb oxygen and release carbon dioxide. This oxygenated blood then moves back to the heart. The heart, veins, arteries, and capillaries are the main constituents of the circulatory system.

This deoxygenated blood leaves the right ventricle of the heart and then goes through the pulmonary trunk into the pulmonary artery. The arteries then transport the blood to the capillary beds of the lungs. With this, carbon dioxide is released and oxygen is absorbed. This blood, now oxygenated, then flows from the capillary beds into the pulmonary veins and then back to the heart.

Spherically shaped bacteria are known as cocci (singular coccus). A coccus, therefore, is any bacteria having an ovoid, spherical, or a round shape in general. Generally, bacteria are classified based on their shape into three classes; the cocci (round-shaped), the bacillus (rod-shaped), and the spirochetes (spiral-shaped).

The appendicular skeleton consists of bones that function in supporting the appendages. This portion of the skeletal system includes the framework of the limbs, the pelvic girdle, and the shoulder girdle. The seven bones of the appendicular skeleton include the femur, the fibula, tarsal bones, tibia, phalanges, and metatarsal bones. The vertebral column is a part of the axial skeleton which includes the bones of the head, and trunk of vertebrates.

The nucleus is in charge of regulating and controlling all activities done within the cell. It carries the genes and structures containing important hereditary information. Being the most prominent and largest organelle in the cell, the main function of the nucleus is in housing the genetic material (DNA) needed by the cell to ensure cell division and inheritance. It is also a site of RNA or ribonucleic acid synthesis. RNA in turn assists in the production of ribosomes (protein factories of the cell).

Fat is used by the body as a source of fuel. Of the options listed, option C is not a function of fat in the human body as fats are not carriers of water-soluble vitamins. Instead, they are carriers of fat-soluble vitamins (vitamins A, D, E, and K). The cells in our body are covered by a membrane made of phospholipids, cholesterol, and triglycerides. These lipid components affect the arrangement of the membrane and therefore, its fluidity.

Fats also help in offering insulation for bones to limit friction and eliminate physical shock. It also helps in protecting delicate tissues and organs from harm and danger when they come in contact with hard surfaces. The blanket layer formed by subcutaneous fat functions as an insulator for the body against extreme temperatures, and in keeping the general temperature of the body under control.

Bones of the axial skeleton in humans include the skull, the middle ear, the ossicles, the hyoid bone, the rib cage, the sternum, and the vertebral column. The full human skeleton is a combination of the axial skeleton and the appendicular skeleton. With this, the pelvis is not a part of the axial skeleton. Rather, it is a part of the appendicular skeleton

In meiosis, a single diploid cell divides twice to produce four haploid cells, each containing half the amount of genetic information. In mitosis, however, a single cell divides, giving two identical diploid daughter cells, with each having the original amount of genetic information as the parent. Sex cells, sperms in males, and eggs in females are a result of meiosis. Meiosis starts from a parent cell that is diploid but will end up producing four haploid gamete cells.

The cardiovascular system consists of the heart, together with a closed system of vessels which includes the veins, arteries, and capillaries. The capillaries are the most numerous of the blood vessels and they help in forming a connection between the veins and the arteries. Capillaries can also be used for thermoregulation where they can help in regulating body temperature. Through vasoconstriction and vasodilation, capillaries can limit blood speed. Through shunting, blood flow to an area can be restricted during cold weather and through flushing, the blood flow is increased during hotter periods. With this, the body temperature is regulated.

The lymphatic system is a part of the immune system, important for the cleaning within the fluids of the body. It also helps in producing an immune response to a certain disease. The lymphatic system is in no way responsible for the transport of respiratory gases. The lymphatic system has four main functions; maintaining the fluid levels of the body, cellular waste removal, protection of the body from disease-causing organisms, and ensuring a balance in body fluid levels. Although not part of the immune system, the lymphatic system is sometimes referred to as glands. This system is made up of small vesicles known as lacteals. These are used to absorb fat and fat-soluble nutrients in the gut.

Reproductive isolation is required for speciation to occur as it involves all of the mechanisms involved in evolution, including the behaviors and the physiological processes necessary for speciation. In speciation, new species emerge through evolutionary processes, and without reproductive isolation, the members of the species will interbreed freely. With reproductive isolation, however, members of different species are prevented from producing offspring or the offspring are rendered sterile. All of these barriers help maintain the integrity a species has, by reducing the flow of genes between interrelated species. If populations can interbreed, they are considered one species. With this, the integrity of species is maintained and complications are prevented.

With this, plants are capable of getting rigid and getting in shape. Chloroplasts also are found only in plants. This is so because chloroplasts are essential in the photosynthetic process and plants are known to manufacture their own food, unlike animals. Plants cells also contain in them large vacuoles used to store water and food for the future. Animals also have vacuoles but in plants, they are way bigger and more prominent.

With modern taxonomy, both the internal and external structures of an organism can now be studied and this is important in getting information regarding certain organisms related to ecology. Taxonomy has helped to name and group organisms into an organized biological system. A 2% difference in DNA sequence between two organisms is now considered to be enough to classify them as different species. This is what modern taxonomy can do. With this, comparing the difference in length of DNA among different members of a species can help in making nomenclature and classification even more efficient.

The ribosomes can be found in the endoplasmic reticulum. There are two types of endoplasmic reticulum; they are the smooth endoplasmic reticulum and the rough endoplasmic reticulum. The ribosomes are found on the latter. The ribosomes are organelles responsible for the production of proteins. Proteins are made from all amino acids and the ribosomes are the cellular component responsible for this.

In other words, a cell in need of protein can only synthesize proteins by looking for ribosomes. Ribosomes are found in both prokaryotes and eukaryotes and are part of the endomembrane system. When these proteins are synthesized, the Golgi apparatus helps in transporting and modifying the proteins particularly in a eukaryotic cell. These proteins are then transported further via transport vesicles and then taken to the cell surface.

Circadian rhythms are processes that occur in a 24-hour cycle. A good example of a circadian rhythm is the appearance of fireflies at dusk because it happens daily, at a specific time. The time frame between the appearances of fireflies in two days is roughly 24-hours. Another good example of a circadian rhythm is the sleep-wake cycle in man. There is a designated time every day to sleep and this goes on consistently. Also, the opening and closing of petals of flowers is a form of the circadian rhythm.

By phagocytosis, amoebas are capable of feeding and this is a very useful mechanism in the general feeding structure of the amoeba. Amoebas are non-selective in their general nutrition as they will literally eat whatever they can.

Generally, amoeba feeds on other microscopic organisms like bacteria and one-celled algae. To feed, the cytoplasm of the amoeba goes around the prey and then engulfs it, coupled with a drop of water found in the food vacuole. Enzymes are produced and this helps in breaking down the food substance engulfed. This process is known as phagocytosis.

A person who desires to lose weight in a healthy manner should focus on total calorie intake by intentionally cutting the number of calories consumed per day. Keeping a record of the calorie intake of the body is a good way to start as it helps in limiting our total calorie intake and staying healthy. This record will contain in it the types of food consumed and the calorie count of such food products. Foods with high calorie content are limited while those with very low calorie content are taken more.

As a result of our ever changing environment, adaptive evolution leads to a fluctuating change in traits. With evolution leading to changes in organic matter over time, adaptive evolution results from the body’s need to survive or adapt to certain changes in the environment. There is always a constant need to adapt and when evolutionary changes occur as a result of such adaptations, such changes are bound to fluctuate as the environment will most likely change again and the body will be left with the task of adapting to such change.

The nitrogen cycle involves a series of mechanisms leading to the interconversion of nitrogen and nitrogenous compounds gotten from the atmosphere. In the nitrogen cycle, bacteria are very important because atmospheric nitrogen can in no way be directly utilized by plants. Rhizobium, a type of bacteria plays an important role in nitrogen fixation. By converting atmospheric nitrogen to ammonia (NH3) which is then taken by plants to make organic molecules. These molecules containing nitrogen are then passed to animals when these animals consume plants. The nitrogen gotten from these plants by the animals is then infused into the animal’s body or excreted as waste when broken down. This can be seen in urea found in urine.

Amino acids are the building blocks of proteins. A typical amino acid structure consists of a central carbon atom covalently bonded to a carboxyl group, an amino group, and a hydrogen atom. When numerous amino acid structures combine, they form proteins. In order words, proteins are long chain amino acids. The body does not use proteins to create amino acids as proteins are amino acids themselves.

During digestion, proteins are broken down into amino acids and these amino acids are utilized by the body for a variety of functions. Some of these functions include the breaking down of food, for growth of organs as well as the entire body structure, for body tissue repair, and many other functions. The Hemoglobin is made of proteins and it helps in transporting oxygen in the blood. The hemoglobin is located in the red blood cell and about 96% of the dry content of the red blood cell is made up of proteins.