Biology (Unit 1) R#2 Flashcards
What are the 8 life processes that all living organisms do?
Move, Respire, Grow, Respond, Control, Excrete, Nutrition, Reproduce.
What is respiration?
The breakdown of organic molecules to release energy.
Are plants unicellular or multicellular?
Multicellular.
What structure in plants allows them to carry out photosynthesis?
Chloroplasts.
What is the plant cell wall made of?
Cellulose.
How do plants store glucose?
As starch or sucrose.
Are animals unicellular or multicellular?
Multicellular.
Do animal cells have a cell wall?
No.
What system do animals use for coordination?
The nervous system.
How do animals store glucose?
As glycogen.
Are animals capable of movement?
Yes, they can move from one place to another.
What is the fungal cell wall made of?
Chitin.
How do fungi store carbohydrates?
As glycogen.
What is the body of a fungus made of?
Mycelium, which is made of thread-like structures called hyphae.
What is an example of a unicellular fungus?
Yeast.
What is an example of a multicellular fungus?
Mucor (bread mold).
What type of nutrition do fungi use and describe how it works?
Saprotrophic nutrition: Release of extracellular enzymes to digest organic molecules and then absorb organic products
Are protoctists unicellular or multicellular?
Unicellular.
Do protoctists have a cell wall?
No.
Give an example of an animal-like protoctist.
Amoeba.
Give an example of a plant-like protoctist.
Chlorella.
Which protoctist causes malaria?
Plasmodium.
Pathogenic
Do bacteria have a nucleus?
No, they have circular DNA instead.
What is the bacterial cell wall made of?
Murein.
What additional structures do bacteria have for movement and protection?
A slime capsule and a flagellum.
What are plasmids?
Rings of DNA in bacteria.
Give an example of useful bacteria.
Lactobacillus (used in yogurt production).
Which bacteria causes pneumonia?
Pneumococcus.
Pathogenic
What are the differences between eukaryotic and prokaryotic organisms? (4 points)
- Eukaryotic organisms have a nucleus while prokaryotic organisms don’t
- Eukaryotic organisms have mitochondria while prokaryotic organisms don’t
- Eukaryotic organisms have linear DNA while prokaryotic organisms have circular DNA
- Eukaryotic don’t have plasmids while prokaryotic organisms have plasmids
Are viruses considered living organisms? Why or why not?
No, because they do not grow, respire, or require nutrition.
Do viruses have a cellular structure?
No.
Are viruses pathogenic?
Yes, they can cause diseases.
Which virus causes AIDS?
HIV.
Which virus damages plant chloroplasts?
Tobacco Mosaic Virus.
What are the two main components of a virus?
A protein coat (capsid) and genetic material (DNA or RNA).
What is the function of the cell membrane?
It is semi-permeable and controls the movement of substances in and out of the cell.
What is the role of the cytoplasm in a cell?
It is the site of chemical reactions.
What does the nucleus contain, and what is its function?
It contains DNA and controls cell functions.
What is the function of mitochondria?
It is the site of aerobic respiration and releases energy.
What is the role of ribosomes?
They are the site of protein synthesis.
What is the function of the cell wall in a plant cell?
It is made of cellulose, protects the cell, and gives it shape.
What do chloroplasts do?
They are the site of photosynthesis and contain chlorophyll to absorb light.
What is stored in the sap vacuole?
Water and mineral ions.
What is the correct order of biological organization from simplest to most complex?
Cell → Tissue → Organ → Organ System → Organism.
What is a tissue?
A group of similar cells that perform a specific function.
What is an organ?
A structure made of different tissues working together to perform functions.
What is diffusion?
The movement of particles from an area of high concentration to an area of lower concentration down a concentration gradient.
Give two examples of diffusion in living organisms.
- Gas exchange in humans
- Gas exchange in plants
How does surface area to volume ratio affect diffusion?
A larger surface area to volume ratio increases the rate of diffusion.
How does diffusion distance affect the rate of diffusion?
A shorter diffusion distance increases the rate of diffusion.
Example: Alveoli have thin walls to provide a shorter diffusion distance for faster gas exchange.
How does the concentration gradient affect diffusion?
A steeper concentration gradient increases the rate of diffusion.
How does temperature affect diffusion?
Higher temperature increases diffusion rate because particles gain more kinetic energy and move faster.
How does particle size affect diffusion?
Smaller particles diffuse faster.
What is osmosis?
The movement of water molecules from a high water potential (dilute solution) to a lower water potential (concentrated solution) through a semi-permeable membrane.
What happens to an animal cell in a dilute solution?
Water moves into the cell by osmosis, causing it to swell and burst (as it has no cell wall).
What happens to an animal cell in a concentrated solution?
Water moves out of the cell by osmosis, causing it to shrink.
What happens to a plant cell in a dilute solution?
Water moves into the cell by osmosis, making it turgid (it does not burst due to the presence of a cell wall).
What happens to a plant cell in a concentrated solution?
Water moves out by osmosis, causing the cell to become flaccid or plasmolysed.
What is active transport?
The movement of particles from a low concentration to a high concentration against a concentration gradient using energy.
What are the differences between active transport and diffusion? (2 deffinitions + 3 points)
- Active transport: substances move from low to higher concentration against a concentration gradient
- Diffusion: substances move from a high to a lower concentration down a concentration gradient
- Acive transport requires energy while diffusion doesn’t
- Diffusion is passive while active transport is active
- Active transport occurs in living organisms only
What elements make up carbohydrates?
Carbon (C), Hydrogen (H), and Oxygen (O).
What is the simplest form of carbohydrates?
Glucose (simple sugars/monosaccharides).
What are complex forms of carbohydrates?
Starch, glycogen, and cellulose (polysaccharides).
What is the main importance of carbohydrates?
They serve as a source of energy.
What elements make up lipids?
Carbon (C), Hydrogen (H), and Oxygen (O).
What are lipids made of?
One glycerol molecule and three fatty acids.
What are the main functions of lipids?
They provide energy, insulation, and serve as a store of energy.
What elements make up proteins?
Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N).
What are proteins made of?
Amino acids.
What are the main functions of proteins?
They are used for growth, repair of cells, and enzyme formation.
- What test is used for starch?
- What is the positive and negative result for the starch test?
- Iodine solution.
- Positive: blue-black | Negative: yellow (orange).
- How is a reducing sugar (glucose) test conducted?
- What are the possible positive results for a reducing sugar test?
- Add Benedict’s solution and heat in a water bath.
- Green, yellow, orange, or brick-red.
- What test is used for proteins?
- What is the positive and negative result for the protein test?
- Biuret solution.
- Positive: purple (lilac) | Negative: blue.
- How is a lipid test conducted?
- What are the positive and negative results for the lipid test?
- Emulsion test: add ethanol and water to the sample and shake.
- Positive: white | Negative: clear.
What is the definition of an enzyme?
A protein that acts as a biological catalyst, speeding up the rate of chemical reactions without being used up or changed.
What is meant by the term metabolic?
Chemical reactions that occur within living organisms
How do enzymes work? (Not chemistry)
Each enzyme has a specific shape (active site) that complements a substrate molecule.
How does temperature affect enzyme activity?
- At low temperatures, enzymes are inactive because particles move slowly, leading to fewer collisions with the active site.
- As temperature increases, particles gain kinetic energy and move faster, leading to more collisions.
- At high temperatures, the active site changes shape, and the substrate no longer fits (enzyme denatures).
What happens to enzyme activity at optimum temperature?
The enzyme works at its highest efficiency.
How does pH affect enzyme activity?
Each enzyme has an optimum pH; changing the pH can denature the enzyme.
What is the word equation for photosynthesis?
Carbon dioxide + water → glucose + oxygen.
What is the balanced chemical equation for photosynthesis?
6CO₂ + 6H₂O → (light) C₆H₁₂O₆ + 6O₂.
What adaptations help the leaf with photosynthesis?
- The leaf is thin, leading to a shorter diffusion distance for quicker diffusion.
- The leaf is thin, allowing light to easily penetrate through.
- Leaves in the shade have more chloroplasts and a darker color to absorb more light.
What is the function of the waxy cuticle?
It reduces water loss from the leaf.
What is the function of the upper epidermis?
It is thin and transparent to allow light to pass through.
How is the palisade mesophyll adapted for photosynthesis?
- Contains a large number of chloroplasts for photosynthesis.
- Tightly packed and close to the upper epidermis for maximum light absorption.
How is the spongy mesophyll adapted for gas exchange?
- Loosely packed with air gaps to increase surface area for rapid diffusion of gases.
- Has a layer of moisture to dissolve gases.
What is the function of the lower epidermis?
- Contains stomata through which gases diffuse in and out.
- Has guard cells that control the opening and closing of stomata.
How does light intensity affect the rate of photosynthesis?
As light intensity increases, the rate of photosynthesis increases.
How does CO₂ concentration affect the rate of photosynthesis?
As CO₂ concentration increases, the rate of photosynthesis increases.
How does temperature affect the rate of photosynthesis?
- As temperature increases, the rate of photosynthesis increases because particles gain kinetic energy and collide more.
- At very high temperatures, the rate decreases because enzymes denature, and stomata close to prevent water loss, stopping CO₂ from entering the leaf.
What is the function of nitrates in plants?
Nitrates are needed to make amino acids, which build proteins.
What is the function of magnesium in plants?
Magnesium is needed to make chlorophyll, which absorbs light for photosynthesis.
How does light intensity affect the rate of photosynthesis?
The closer the light source, the higher the rate of photosynthesis, as more stomata remain open, allowing more CO₂ to enter.
How does temperature affect the rate of photosynthesis in an experiment?
- Higher temperature increases the kinetic energy of gas particles, increasing the rate of diffusion and photosynthesis.
- At very high temperatures, stomata close to reduce water loss, stopping CO₂ from entering and stopping photosynthesis.
How can CO₂ concentration be manipulated in an experiment?
By adding different concentrations of potassium hydrogen carbonate (KHCO₃).
Why is a plant kept in a dark room for 24 hours before testing for starch?
To destarch the plant, ensuring only respiration occurs and no photosynthesis.
- How is starch tested in a leaf? (5 steps)
- What are the possible results of the starch test?
- Cover part of the leaf with black paper and expose the plant to light.
- Boil the leaf in water to denature enzymes.
- Boil the leaf in ethanol in a water bath to remove chlorophyll.
- Soften the leaf in cold water.
- Add iodine solution.
Possible results:
* Positive (+ve): Blue-black (starch present).
* Negative (-ve): Brown (no starch present).
Why is the leaf thin?
To provide a shorter diffusion distance for rapid gas exchange.
How does the spongy layer help with gas exchange?
It has air gaps that increase surface area for rapid gas exchange (higher SA to volume ratio).
What is the function of stomata in the lower epidermis?
Stomata allow gases to diffuse in and out of the leaf. (CO2 in, O2 out)
What is the role of guard cells?
They control the opening and closing of stomata.
Why is moisture present between spongy mesophyll cells?
To dissolve gases, allowing easier diffusion.
What happens at high light intensity in terms of the movement of CO₂?
The rate of photosynthesis is higher than the rate of respiration, so:
- CO₂ diffuses in.
- O₂ diffuses out.
What happens at low light intensity (dark conditions) in terms of the movement of CO₂?
The rate of respiration is higher than the rate of photosynthesis, so:
- CO₂ diffuses out.
- O₂ diffuses in.
What are the color changes of hydrogen carbonate indicator based on CO₂ concentration?
- Acidic (high CO₂): Yellow.
- Neutral CO₂ level: Red.
- Alkaline (low CO₂): Purple.
How is hydrogen carbonate indicator used in an experiment?
A plant is placed underwater with hydrogen carbonate indicator to observe CO₂ changes.
What happens if the rate of respiration is greater than the rate of photosynthesis? (Effects on hydrogen carbonate indicator)
- CO₂ concentration increases (CO₂ is an acidic gas).
- Hydrogen carbonate indicator turns yellow.
What happens if the rate of respiration is lower than the rate of photosynthesis? (Effects on hydrogen carbonate indicator)
- CO₂ concentration decreases (CO₂ is used up in photosynthesis).
- Hydrogen carbonate indicator turns purple.
What happens to guard cells when there is high light intensity? (mechanism of guard cells, 3 points)
- Guard cells actively uptake mineral ions, increasing cytoplasm concentration (low water potential).
- Water enters guard cells by osmosis.
- Guard cells become turgid, stretching the cell and opening stomata.
What happens to guard cells in the dark? (mechanism of guard cells, 3 points)
- Mineral ions leave the guard cell.
- Water moves out of the cell by osmosis.
- Guard cells become flaccid, causing stomata to close.
What is a balanced diet?
A diet that includes the seven essential nutrients in the correct proportions.
What are the seven essential nutrients and their functions? (list all 7)
Carbohydrates – (soluble form: glucose)
* Main source of energy
Fats – (Soluble form: 1 glycerol + 3 fatty acids)
* Source and store of energy.
* Provides insulation.
* Protects organs.
Proteins – (Soluble form: amino acids)
* Growth.
* Hormones.
* Enzymes.
* Tissue repair.
* Antibodies.
Minerals
* Iron: Needed to make haemoglobin in red blood cells.
* Calcium: Needed to build bones and teeth.
Vitamins
* Vitamin A: Helps with night vision.
* Vitamin D: Helps absorb calcium and prevents rickets.
* Vitamin C: Supports immunity, keeps gums/skin healthy, prevents scurvy.
Fibres
* Stimulates peristalsis.
* Prevents colon cancer.
* Prevents constipation.
Water
* Acts as a solvent/transport medium.
* Helps cool body temperature.
How does age affect diet?
Young people need more proteins (for growth) and carbohydrates (for energy).
How does activity level affect diet?
Athletes and construction workers need more carbs (for energy) and proteins (for muscle growth).
How does gender affect diet?
- Males need more carbs (higher activity levels).
- Males need more proteins (to maintain muscle mass).
Why do pregnant women need more nutrients? (Give 4 examples)
They require additional nutrients for their own needs and foetal development, including:
* Carbs & proteins – For foetal growth.
* Vitamin C – For skin health and immunity.
* Vitamin D & calcium – For bone and teeth formation.
* Iron – For haemoglobin production (to compensate for blood loss due to menstruation).
What are the five stages of nutrition?
- Ingestion – Eating food.
- Digestion:
Mechanical digestion: Breaking food into smaller pieces to increase surface area.
Chemical digestion: Using enzymes to break down food into smaller soluble molecules.
- Absorption – Transporting digested food molecules from the small intestine to the bloodstream.
- Assimilation – Using absorbed nutrients in body cells.
- Egestion – Excreting undigested food through the anus.
What happens in the mouth? (2 points)
- Mechanical digestion: Chewing food.
- Chemical digestion: Salivary amylase breaks down starch → maltose.
What is the function of the oesophagus?
Transports the food bolus from the mouth to the stomach using peristalsis.
What is peristalsis?
Alternating contraction and relaxation of muscles in the digestive tract to push food forward.
What happens in the stomach? (2 points)
- Mechanical digestion: Churning food.
- Chemical digestion: Pepsin enzyme breaks down proteins → amino acids in an acidic HCl environment.
What happens in the duodenum? (2 points)
The duodenum receives:
Bile juice (from liver/gallbladder):
* Neutralises stomach acid.
* Emulsifies fats (breaks them into smaller droplets).
Pancreatic juice (from pancreas):
* Amylase: Starch → Maltose.
* Trypsin: Proteins → Amino acids.
* Lipase: Fats → 1 glycerol + 3 fatty acids.
What is the emulsification of fats?
the breakdown of fats into small droplets for larger surface area for faster action of lipase enzyme
What happens in the Ileum? (2 points)
- Further digestion using enzymes (e.g., maltase: maltose → glucose).
- Absorption of nutrients by villi.
How are villi adapted for absorption? (5 points)
- Thin walls → Faster diffusion.
- Dense capillary network → Maintains steep concentration gradient.
- Microvilli → Increase surface area.
- Lacteal vessels → Absorb fatty acids & glycerol.
- Many mitochondria → Provide energy for active transport.
What happens in the large intestine? (2 points)
- Absorbs water.
- Faeces stored in rectum and egested via anus.
How can you measure the energy content of food? (7 points)
- Weigh the food sample.
- Mount the food on a needle.
- Fill a test tube with 50 cm³ of water, measure initial temperature.
- Ignite the food sample and place it under the tube.
- Let it burn completely, measure final water temperature.
- Calculate energy using:
Energy = 50 × 4.2 × ΔT - Repeat for accuracy.
What are the disadvantages of this simple method? (Measuring energy content in foods, 4 points)
Inaccurate calculations and measurments due to:
* Incomplete combustion due to lack of oxygen.
* Heat loss to surroundings.
* Uneven heat distribution in water.
* Sample transfer must be fast to retain heat.
How does a calorimeter improve accuracy? (4 points)
- Provides oxygen for complete combustion.
- Enclosed space reduces heat loss.
- Copper pipe efficiently transfers heat to water.
- Stirrer ensures even heat distribution.
What is aerobic respiration?
Aerobic respiration is the breakdown of nutrient molecules in the presence of oxygen to release energy.
What is the word and chemical equation for aerobic respiration?
Word equation:
* Glucose + Oxygen → Water + Carbon Dioxide + ATP (energy)
Chemical equation:
* C6H12O6 + 6O2 → 6H2O + 6CO2 + ATP
Where does aerobic respiration take place?
It occurs in the mitochondria of the cell.
What is anaerobic respiration?
Anaerobic respiration is the breakdown of nutrient molecules in the absence of oxygen to release energy.
What is the word equation for anaerobic respiration in yeast cells?
Glucose → Ethanol + Carbon Dioxide
What is the word equation for anaerobic respiration in muscle cells?
Glucose → Lactic Acid
Where does anaerobic respiration take place?
It occurs in the cytoplasm of the cell.
Compare between areobic and anaerobic respiration. (4 points each)
Aerobic Respiration
* Occurs in presence of oxygen
* Takes place in mitochondria
* Produces more ATP (energy)
* Waste products: Water + Carbon Dioxide
Anaerobic Respiration
* Occurs in absence of oxygen
* Takes place in cytoplasm
* Produces less ATP (energy)
* Waste products:
1. Yeast cells: Ethanol + CO₂
2. Muscle cells: Lactic acid |
What is the function of the trachea? (2 points)
The trachea is lined with ciliated epithelial cells that:
- Secrete mucus to trap dust and bacteria.
- Have cilia that sweep the mucus out of the airways
How does oxygen diffuse in the alveoli?
Oxygen diffuses from the alveoli into the blood because:
- High concentration of O₂ in the alveoli
- Low concentration of O₂ in the blood
How does carbon dioxide diffuse in the alveoli?
Carbon dioxide diffuses from the blood into the alveoli because:
- High concentration of CO₂ in the blood
- Low concentration of CO₂ in the alveoli
What are the adaptations of the alveoli for gas exchange? (4 points)
- Thin walls – Short diffusion distance for rapid gas exchange.
- Large number of alveoli – Increases surface area for faster diffusion.
- Surrounded by blood capillaries – Maintains a steep concentration gradient.
- Moist surface – Helps dissolve gases for diffusion.
What happens during breathing in (inhalation)? (3 points)
- External intercostal muscles contract – Ribcage moves up and out, increasing thorax volume.
- Diaphragm contracts and flattens, increasing thorax volume.
- Increased thorax volume → decreased pressure, so air enters the lungs.
What happens during breathing out (exhalation)? (3 points)
- Internal intercostal muscles contract – Ribcage moves down and in, decreasing thorax volume.
- Diaphragm relaxes – Returns to dome shape, decreasing thorax volume.
- Decreased thorax volume → increased pressure, so air exits.
Why does breathing rate increase during exercise? (2 points)
- More oxygen is needed for aerobic respiration in muscle cells to release energy for muscle contraction.
- Helps remove excess CO₂ produced during respiration.
Why does breathing rate remain high after exercise? (2 points)
- Oxygen is needed to oxidize lactic acid produced during anaerobic respiration.
- This is called oxygen debt repayment.
What harmful substances does tobacco contain?
Tobacco contains nicotine, tar, and carbon monoxide.
How does nicotine affect the body? (2 points)
- Raises blood pressure
- Increases risk of heart attacks
How does carbon monoxide affect the body? (2 points)
- Binds with haemoglobin in red blood cells, forming carboxyhaemoglobin.
- Reduces the concentration of oxygen in the blood.
How does tar affect the lungs? (3 points)
- Causes lung cancer.
- Damages cilia, preventing the removal of mucus, leading to chronic bronchitis.
- Damages alveoli, reducing surface area for gas exchange, causing lung emphysema.
