Science Exam With MCQ Questions

Evolution refers to the process of change in species over a long period of time. It involves genetic variations and natural selection, leading to the development of new species or the modification of existing ones. This process is supported by extensive scientific evidence from various fields such as paleontology, genetics, and comparative anatomy. Therefore, the statement that evolution is the change in species over a long period of time is true.

The respiratory system is responsible for bringing oxygen into the body. It consists of organs such as the nose, trachea, and lungs, which work together to inhale oxygen from the air and deliver it to the bloodstream. This oxygen is then transported to cells throughout the body, where it is used for various metabolic processes. Therefore, the statement is true.

The given pathway of food through the digestive system is correct. Food enters the mouth, passes through the esophagus, and reaches the stomach where it is further digested. From the stomach, it moves into the small intestine where nutrients are absorbed into the bloodstream. The remaining undigested food then enters the large intestine where water is absorbed, and finally, the waste material is eliminated through the rectum and anus, not the urethra, into the toilet. Therefore, the answer is true.

Cardiac tissue is the correct answer because it is the only type of tissue that is specifically found in the heart. Epithelial tissue is found in various parts of the body, not just the heart. Skeletal tissue is associated with the skeletal system, not the heart. "None of above" is not a valid option as cardiac tissue does exist and is unique to the heart.

Saliva is the correct answer because it is a substance in the mouth that contains enzymes which begin the process of chemical digestion. Saliva contains the enzyme amylase, which breaks down carbohydrates into smaller molecules. This process is the first step in the digestion of food in the mouth before it moves to the stomach for further digestion.

A stimulus refers to a change in an organism's surroundings that triggers a reaction. It can be any external or internal factor that provokes a response from an organism. This response can be in the form of an action or a change in behavior. The stimulus can vary widely, such as a sudden loud noise causing a startle reflex or a change in temperature leading to an organism seeking shelter. Therefore, the correct answer is "a change in an organism's surroundings that causes the organism to react."

The right ventricle is responsible for pumping oxygen-poor blood to the lungs. After receiving deoxygenated blood from the right atrium, the right ventricle contracts to push the blood through the pulmonary artery and into the lungs, where it will be oxygenated. This oxygen-rich blood will then return to the heart through the left atrium and left ventricle before being pumped out to the rest of the body.

Veins are the blood vessels that carry blood away from the heart. They transport deoxygenated blood from the body's tissues back to the heart, where it can be oxygenated again. Unlike arteries, veins have thinner walls and contain valves that prevent the backward flow of blood. This allows veins to efficiently return blood to the heart, completing the circulatory system. Capillaries, on the other hand, are tiny blood vessels that connect arteries and veins, facilitating the exchange of oxygen, nutrients, and waste products between the blood and body tissues.