Digestion
What is digestion, and why is it important for the human body?
Digestion is the process by which complex food substances are broken down into simpler, soluble substances that can be absorbed by the body. It is important because the body needs these nutrients for energy, growth, repair of tissues, and to maintain overall health.
What is the nervous system, and what are its main functions?
The nervous system is a control and coordination system of the body. Its main functions are to receive stimuli, transmit nerve impulses, process information, and coordinate responses to maintain normal body activities.
What is homeostasis?
Homeostasis is the process by which the body maintains a stable internal environment despite changes in the external environment.
What is respiration, and why is it important for living organisms?
Respiration is the process by which living organisms release energy from food. It is important because the energy released is needed for growth, movement, repair, and other life processes.
What is cellular transport, and why is it important for cells?
Cellular transport is the movement of substances into and out of the cell through the cell membrane. It is important because it allows cells to obtain nutrients and oxygen, remove waste products, and maintain a stable internal environment.
Describe the role of saliva in digestion. Which enzyme is present in saliva and what does it do?
Saliva helps in digestion by moistening and softening food, making it easier to swallow. It contains the enzyme salivary amylase, which begins the digestion of starch by breaking it down into simpler sugars like maltose
Name the main parts of the nervous system and state one function of each.
The nervous system is divided into:
Central Nervous System (CNS): Includes the brain and spinal cord; it controls and coordinates body activities.
Peripheral Nervous System (PNS): Consists of nerves; it carries messages between the CNS and different parts of the body.
Why is homeostasis important for the human body?
Homeostasis is important because it keeps internal conditions such as temperature, blood sugar level, and water balance within normal limits, allowing enzymes and cells to function properly
Define aerobic respiration and anaerobic respiration.
Aerobic respiration is the breakdown of glucose in the presence of oxygen to release energy.
Anaerobic respiration is the breakdown of glucose in the absence of oxygen to release energy.
Define passive transport and name its main types.
Passive transport is the movement of substances across the cell membrane without the use of energy. The main types of passive transport are diffusion, osmosis, and facilitated diffusion.
Explain how proteins are digested in the human digestive system. Name the enzymes involved and where they act.
Protein digestion begins in the stomach, where the enzyme pepsin breaks proteins into smaller peptides in an acidic medium. In the small intestine, enzymes such as trypsin and peptidases further break these peptides into amino acids, which can be absorbed into the bloodstream.
Draw and describe the structure of a neuron. Mention the function of each part.
A neuron has three main parts:
Dendrites: Receive nerve impulses from other neurons.
Cell body (cyton): Contains the nucleus and controls cell activities.
Axon: Carries nerve impulses away from the cell body.
The axon may be covered by a myelin sheath, which helps in faster transmission of impulses.
Explain how the body maintains a constant body temperature.
When body temperature rises, sweating occurs and blood vessels near the skin dilate to release heat. When body temperature falls, shivering occurs and blood vessels constrict to conserve heat.
Compare aerobic and anaerobic respiration in terms of oxygen requirement, end products, and energy released.
Aerobic respiration requires oxygen and produces carbon dioxide and water, releasing a large amount of energy. Anaerobic respiration does not require oxygen and produces lactic acid in animals or alcohol and carbon dioxide in plants and yeast, releasing much less energy.
Explain diffusion and osmosis with examples.
Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration. For example, oxygen diffuses from the blood into body cells.
Osmosis is the diffusion of water through a semi-permeable membrane from a region of high water concentration to a region of low water concentration, such as water entering plant root hair cells.
How do digestive enzymes work under specific conditions such as temperature and pH? Give examples from different parts of the digestive system.
Digestive enzymes work best at specific temperatures and pH levels. Most enzymes function best at body temperature (around 37°C). For example, pepsin works best in the acidic pH of the stomach, while amylase and trypsin work best in the alkaline conditions of the small intestine. If the conditions are not suitable, enzymes may work slowly or become inactive.
Explain how a nerve impulse travels through a neuron.
A nerve impulse starts at the dendrites, passes through the cell body, and travels along the axon to the axon terminals. From there, it is transmitted to the next neuron or effector through a synapse.
Describe the role of the kidneys in maintaining homeostasis.
The kidneys help maintain homeostasis by regulating water balance, removing waste products like urea, and maintaining the balance of salts and pH in the blood.
Explain the process of aerobic respiration in humans, including where it occurs in the cell.
In humans, aerobic respiration occurs mainly in the mitochondria. Glucose is completely broken down using oxygen to form carbon dioxide and water, releasing energy in the form of ATP.
Define active transport and explain how it is different from passive transport.
Active transport is the movement of substances across the cell membrane against the concentration gradient using energy (ATP). Unlike passive transport, it requires energy and can move substances from a lower concentration to a higher concentration.
Predict what would happen if the pancreas stopped producing digestive enzymes. How would this affect the digestion of carbohydrates, proteins, and fats?
If the pancreas stopped producing digestive enzymes, digestion would be severely affected. Carbohydrates would not be properly broken down due to lack of pancreatic amylase, proteins would not be fully digested without trypsin, and fats would not be digested efficiently due to lack of lipase. This would lead to poor absorption of nutrients, weight loss, and weakness.
What would happen if the myelin sheath of a neuron is damaged?
If the myelin sheath is damaged, the speed of nerve impulse transmission would decrease. This may cause delayed responses, poor coordination, or loss of muscle control.
Explain the mechanism of negative feedback using blood glucose regulation as an example.
When blood glucose levels rise, the pancreas releases insulin, which helps cells absorb glucose and lowers blood sugar levels. When blood glucose levels fall, the pancreas releases glucagon, which increases blood glucose levels. This process helps maintain a stable blood glucose level.
What happens in muscle cells during vigorous exercise when oxygen supply is insufficient? Explain the effects on the body.
During vigorous exercise, muscle cells may undergo anaerobic respiration due to lack of oxygen. This leads to the formation of lactic acid, which causes muscle fatigue and cramps. Oxygen debt is created, which is repaid by increased breathing after exercise.
Describe the types of active transport and explain their importance in maintaining cell functions.
Types of active transport include ion pumps (such as the sodium-potassium pump) and endocytosis and exocytosis. These processes help maintain proper ion balance, allow cells to take in large molecules, and remove substances, which is essential for normal cell function.