Biology

Typhus is a disease transmitted by fleas, specifically the body louse flea, whereas smallpox, tetanus, and yellow fever are not spread by fleas. This makes option C the correct answer.

A frog's heart has three chambers: two atria and one ventricle. This structure allows some mixing of oxygenated and deoxygenated blood, which is characteristic of amphibians.

Multiple authoritative sources, including sonographic studies and anatomical references, indicate that the average length of an adult human kidney is approximately 10 to 11 cm, typically ranging from about 10 to 13 cm. This range fits best with option C (10 cm to 13 cm). The originally marked option B (8 cm to 10 cm) is slightly below the average kidney length reported in healthy adults. Therefore, option C is the most accurate choice based on current medical literature.

The average weight of a human heart is approximately 300 to 350 grams, with 350 grams being a commonly accepted average for adults. This makes option B the most accurate choice.

White blood cells are also called leucocytes, which are part of the immune system and help fight infections. Thrombocytes are platelets involved in blood clotting, and erythrocytes are red blood cells that carry oxygen.

Entomology is the branch of zoology that deals specifically with the study of insects, making option B the correct answer. Ichthyology is the study of fish, zoology is the broader study of animals, and botany is the study of plants.

Nitrogen is a key element in proteins, which are essential components of plants and animals. Proteins contain nitrogen in their amino acid structures, unlike minerals, fats, or carbohydrates which do not contain nitrogen as a primary element.

Ichthyology is the branch of zoology that deals with the study of fish. Entomology is the study of insects, and ecology is the study of interactions between organisms and their environment.

During a total solar eclipse, sunlight is temporarily blocked, causing a significant decrease in light intensity. Since photosynthesis depends on light, its rate decreases, while respiration continues unaffected. Therefore, a decrease in the rate of photosynthesis is most likely.

The cerebrum is the largest part of the human brain, responsible for higher brain functions such as thought and action. The cerebellum, brainstem, and pituitary gland are smaller parts with different functions.