Questions and Answers
What criteria do we use to decide whether something is alive?
Criteria include movement, growth, respiration, and reproduction.
What are outside raw materials used for by an organism?
Outside raw materials are used for energy, growth, and cellular functions.
What processes would you consider essential for maintaining life?
Essential processes include nutrition, respiration, and excretion.
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
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What is the role of the acid in our stomach?
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What is the function of digestive enzymes?
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How is the small intestine designed to absorb digested food?
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Where do plants get each of the raw materials required for photosynthesis?
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What are the differences between autotrophic nutrition and heterotrophic nutrition?
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What change is observed in the lime water and how long does it take for this change to occur when carbon dioxide is bubbled into it?
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What does the fermentation of fruit juice or sugar solution with yeast produce?
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What are the main products of aerobic respiration?
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What advantage does a terrestrial organism have over an aquatic organism in obtaining oxygen for respiration?
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What are the different ways in which glucose is oxidized to provide energy in various organisms?
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How is oxygen and carbon dioxide transported in human beings?
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How are the lungs designed in human beings to maximize the area for exchange of gases?
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What are the components of the transport system in human beings? What are the functions of these components?
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Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?
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What are the components of the transport system in highly organized plants?
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How are water and minerals transported in plants?
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How is food transported in plants?
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How is urine produced in human beings?
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Describe the structure and functioning of nephrons.
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What are the methods used by plants to get rid of excretory products?
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How is the amount of urine produced regulated?
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The kidneys in human beings are a part of the system for:
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The xylem in plants is responsible for:
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The autotrophic mode of nutrition requires:
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The breakdown of pyruvate to give carbon dioxide, water, and energy takes place in:
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How are fats digested in our bodies? Where does this process take place?
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What is the role of saliva in the digestion of food?
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What are the necessary conditions for autotrophic nutrition and what are its by-products?
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What are the differences between aerobic and anaerobic respiration?
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How are the alveoli designed to maximize the exchange of gases?
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What would be the consequences of a deficiency of hemoglobin in our bodies?
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Describe double circulation in human beings. Why is it necessary?
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What are the differences between the transport of materials in xylem and phloem?
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Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.
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Study Notes
Characteristics of Life
- Movement is a common characteristic of living beings, but it is not a defining characteristic
- Even when a living organism is asleep, it still performs maintenance functions that keep it alive
- Molecular movements are necessary for life, and are present in all living organisms
Life Processes
- Life processes are the maintenance functions that all living organisms perform to stay alive
- These processes are necessary to prevent the breakdown of the organism's structure
- Energy is needed to perform these processes, and is obtained from outside the body
Nutrition
- Nutrition is the process by which living organisms obtain energy and materials from the environment
- There are two types of nutrition: autotrophic and heterotrophic
- Autotrophic organisms (e.g. plants) make their own food using sunlight and carbon dioxide
- Heterotrophic organisms (e.g. animals) obtain energy and materials from other organisms
Autotrophic Nutrition
- Autotrophic organisms use photosynthesis to convert sunlight and carbon dioxide into energy
- Photosynthesis occurs in specialized organelles called chloroplasts
- Chlorophyll is essential for photosynthesis
- Carbon dioxide and water are absorbed by the plant and converted into carbohydrates
Heterotrophic Nutrition
- Heterotrophic organisms obtain energy and materials from other organisms
- There are several strategies for heterotrophic nutrition, including:
- Breaking down food outside the body and then absorbing it (e.g. fungi)
- Taking in whole food particles and breaking them down inside the body (e.g. animals)
- Deriving nutrition from plants or animals without killing them (e.g. parasites)
Digestive System
- The digestive system is specialized to break down food and absorb nutrients
- In single-celled organisms, food is taken in by the entire surface of the cell
- In multi-celled organisms, different parts of the body become specialized to perform different functions
- In humans, the alimentary canal is a long tube that extends from the mouth to the anus, with different regions specializing in different functions
Human Digestion
- The mouth breaks down food using teeth and saliva
- Saliva contains enzymes that break down starches into simpler sugars
- The broken-down food is then absorbed into the bloodstream and transported to the rest of the body### Digestion and Absorption
- Food consumption: Saliva is secreted by salivary glands, containing an enzyme called salivary amylase that breaks down starch into sugar.
- Mechanical digestion: Food is mixed with saliva by the muscular tongue while chewing, and then swallowed.
- Peristaltic movements: Muscles in the lining of the alimentary canal rhythmically contract to push food forward through the digestive tube.
- Stomach: Muscular walls mix food with digestive juices, including hydrochloric acid and pepsin, which facilitate protein digestion.
- Small intestine: Longest part of the alimentary canal, with a large surface area for absorption due to extensive coiling and villi (finger-like projections).
- Digestion and absorption: Enzymes from the liver and pancreas break down carbohydrates, proteins, and fats, which are then absorbed into the bloodstream.
Respiration
- Breathing: Oxygen is taken in and carbon dioxide is released through the mouth and nostrils, filtered and moisturized in the throat and lungs.
- Lung structure: Alveoli provide a large surface area for gas exchange, with an extensive network of blood vessels for oxygen and carbon dioxide transport.
- Respiratory pigments: Haemoglobin in red blood cells has a high affinity for oxygen, carrying it from the lungs to tissues and releasing it.
- Carbon dioxide transport: Mostly dissolved in water, with some bound to haemoglobin.
Transportation in Human Beings
- Blood composition: Plasma (fluid medium) transports food, oxygen, and waste materials, while red blood cells carry oxygen.
- Haemoglobin: Normal range in human beings varies by age and sex, with differences in levels between children and adults, men and women.
- Haemoglobin levels in animals: Vary by species, age, and sex, with differences in levels between calves, male and female animals.### The Heart and Circulation
- The heart is a muscular organ that pumps blood throughout the body.
- The heart has different chambers to prevent oxygen-rich blood from mixing with carbon dioxide-rich blood.
- Oxygen-rich blood from the lungs comes to the left atrium, then to the left ventricle, and is pumped out to the body.
- De-oxygenated blood comes from the body to the right atrium, then to the right ventricle, and is pumped to the lungs for oxygenation.
Blood Pressure
- Blood pressure is the force of blood against the walls of blood vessels.
- Blood pressure is higher in arteries than in veins.
- Systolic pressure is the pressure during ventricular contraction, and diastolic pressure is the pressure during ventricular relaxation.
- Normal blood pressure is around 120/80 mmHg.
Blood Vessels
- Arteries carry blood away from the heart to the organs.
- Arteries have thick, elastic walls to withstand high pressure.
- Veins collect blood from organs and bring it back to the heart.
- Veins have valves to ensure blood flows in one direction.
Capillaries
- Capillaries are the smallest blood vessels, with walls one-cell thick.
- Exchange of materials between blood and surrounding cells takes place across the thin walls of capillaries.
Platelets and Lymph
- Platelets help to clot blood and plug leaks in blood vessels.
- Lymph is a fluid that drains from tissues and returns to the blood.
- Lymph carries digested and absorbed fat from the intestine and drains excess fluid from extracellular spaces back into the blood.
Transportation in Plants
- Plants have a separate system of transportation for energy and raw materials.
- Xylem tissue transports water and minerals from roots to leaves.
- Phloem tissue transports products of photosynthesis from leaves to other parts of the plant.
- Transpiration helps to move water and minerals from roots to leaves.
Excretion
- Excretion is the process of removing waste products from the body.
- In humans, the excretory system includes the kidneys, ureters, urinary bladder, and urethra.
- Kidneys filter out waste products from the blood and produce urine.
- Urine is stored in the urinary bladder and released through the urethra.
Kidneys and Urine Production
- Nephrons are the basic filtration units in the kidneys.
- Each nephron consists of a cluster of thin-walled blood capillaries and a cup-shaped end of a tube that collects the filtered urine.
- Substances such as glucose, amino acids, salts, and water are selectively re-absorbed as the urine flows along the tube.
Artificial Kidney (Hemodialysis)
- Artificial kidneys can be used in case of kidney failure.
- Hemodialysis helps to remove waste products from the blood when the kidneys are not functioning properly.
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Description
Explore the essential characteristics and processes that define life, including movement and maintenance functions. Learn how these processes keep living organisms alive.