Cell Transport and Organization in Living Organisms

Diffusion

The net movement of particles from an area of higher concentration to an area of lower concentration.

Osmosis

The net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution) through a partially permeable membrane.

Active Transport

The movement of particles across a cell membrane against a concentration gradient, requiring energy from respiration.

Factors affecting rate of movement of substances into and out of cells

Surface area to volume ratio, distance, temperature, and concentration gradient.

Investigating diffusion/osmosis using living and non-living systems

Practical investigation to observe and measure the movement of substances.

Levels of organisation in organisms

Organelles, cells, tissues, organs, and systems.

Specialised cells

Cells that have adapted to perform a specific function (e.g., red blood cells for oxygen transport, nerve cells for transmitting signals).

Advantages of specialisation/differentiation

Increased efficiency in performing specific functions, leading to complex and highly adapted organisms.

Disadvantages of using stem cells in medicine

Ethical concerns, risk of tumour formation, immune rejection, difficulty controlling differentiation.

Eukaryotes

Organisms whose cells contain a nucleus and other membrane-bound organelles.

Common features of eukaryotic organisms

Presence of nucleus, membrane-bound organelles (e.g., mitochondria, chloroplasts in plants), usually multicellular, can be single-celled.

Plants

Multicellular organisms, their cells contain chloroplasts and are able to carry out photosynthesis. Their cells have cell walls (made of cellulose), store carbohydrates as starch or sucrose. They are often fixed in one place.

Animals

Multicellular organisms, their cells do not contain chloroplasts and are not able to carry out photosynthesis. They have no cell walls. They often store carbohydrate as glycogen.

Fungi

Organisms that are not able to carry out photosynthesis. Their body is usually organised into a mycelium made from thread-like structures called hyphae, which contain many nuclei. Some examples are single-celled, others have cell walls made of chitin. Examples include Mucor (a typical fungal hyphal structure) and yeast (single-celled).

Fungi eat food how? ¯\_ (Owo)_/¯

Feed by squirting their (special gooey sticky white yummy) digestive enzymes onto food material and absorption of the organic products. This is known as saprotrophic nutrition. They may store carbohydrate as glycogen.

Protoctists

Microscopic single-celled organisms. Some, like Amoeba, that live in (ur bath water) pond water have features like an animal cell; while others, like Chlorella, have chloroplasts and are more like plants.

Prokaryotes

Single-celled organisms that lack a nucleus and other membrane-bound organelles.

Bacteria

Microscopic single-celled organisms. They have a cell wall, cell membrane, cytoplasm, and plasmids. They lack a nucleus but contain a circular chromosome of DNA. Some bacteria can carry out photosynthesis but most feed off other living or dead organisms.

Lactobacillus bulgaricus

A rod-shaped bacterium used in the production of yoghurt from (my) milk.

Pneumococcus

A spherical bacterium that acts as the pathogen causing pneumonia (and autism).

Pathogens

Organisms that can cause disease, including fungi, bacteria, protoctists, and viruses (and autism).

Viruses

Not living organisms. They are small particles, smaller than bacteria (but not ur pipi).

Life Processes (MRS GREN)

Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition.

Movement

An action by an organism or part of an organism causing a change of position or place.

Respiration

The chemical reactions that break down nutrient molecules in living cells to release energy for metabolism.

Sensitivity

The ability to detect or sense stimuli in the internal or external environment and to make appropriate responses.

Growth

A permanent increase in size and dry mass by an increase in cell number or cell size or both. (u dont do this :C )

Reproduction

The processes that make more of the same kind of organism. Boutot...

Excretion

The removal from organisms of the waste products of metabolism (chemical reactions in cells including respiration), toxic materials, and substances in excess of requirements.

Nutrition

The taking in of materials for energy, growth, and development; plants require light, carbon dioxide, water, and ions; animals need organic compounds and ions and usually water.

Animal Cell Structure

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes.

Plant Cell Structure

Nucleus, cytoplasm, cell membrane, cell wall, mitochondria, chloroplasts, ribosomes and vacuole.

Differences between plant and animal cells

Plant cells have a cell wall, chloroplasts, and a large permanent vacuole, which animal cells lack. Animal cells may have small temporary vacuoles.

Enzyme

Biological catalysts, which are proteins that speed up the rate of specific biochemical reactions without being used up in the process.

Role of enzymes in metabolic reactions

Speed up metabolic processes, such as respiration, digestion, and synthesis of molecules.

Factors affecting enzyme activity

Temperature and pH.

Effect of temperature on enzyme activity

As temperature increases, enzyme activity increases up to an optimum temperature. Beyond the optimum, the enzyme denatures and activity decreases.

Effect of pH on enzyme activity

Enzymes have an optimum pH. Deviations from the optimum pH can cause denaturation and loss of activity.

Practical: Investigate how enzyme activity can be affected by changes in temperature and pH

Experiments typically involve measuring the rate of a reaction at different temperatures or pH values using an enzyme, e.g., amylase acting on starch.

ATP

Adenosine Triphosphate, the immediate source of energy for cell activities.

Aerobic Respiration (definition)

The release of a relatively large amount of energy in cells by the breakdown of food substances in the presence of oxygen.

Aerobic Respiration (word equation)

Glucose + Oxygen → Carbon Dioxide + Water (+ Energy)

Anaerobic Respiration (definition)

The release of a relatively small amount of energy from food substances in the absence of oxygen.

Anaerobic Respiration in plants and yeast (word equation)

Glucose → Ethanol + Carbon Dioxide (+ Energy)

Anaerobic Respiration in animals (word equation)

Glucose → Lactic Acid (+ Energy)

Practical: Investigate the evolution of carbon dioxide and heat from respiring seeds or other suitable living organisms

Experiments using germinating seeds to show that respiration produces carbon dioxide (e.g., lime water test) and releases heat (e.g., thermometer).

Thorax

The upper part of the trunk, enclosing the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli, and pleural membranes.

Intercostal muscles and diaphragm in ventilation

The intercostal muscles and diaphragm contract and relax to change the volume of the thorax, leading to inhalation and exhalation.

Adaptations of alveoli for gas exchange

Large surface area, thin walls (one cell thick like ur pipi), rich blood supply (capillaries), moist surfaces.

Why u shouldn't smoke (boutot) in relation to the lungs and circulatory system, including coronary heart disease

Damage to cilia, increased mucus production, smoker's cough, bronchitis, emphysema, lung cancer, increased risk of coronary heart disease due to damage to blood vessels and increased blood pressure.

Practical: Investigate breathing in humans

Experiments using a spirometer or measuring lung volumes to understand lung function and breathing rate.

Chemical elements present in carbohydrates,

Carbohydrates: Carbon, Hydrogen, Oxygen (C, H, O); Proteins: Carbon, Hydrogen, Oxygen, Nitrogen (C, H, O, N) and sometimes Sulfur (S);

Chemical elements in my meat (proteins)

Proteins: Carbon, Hydrogen, Oxygen, Nitrogen (C, H, O, N) and sometimes Sulfur (S)

lipids

Lipids: Carbon, Hydrogen, Oxygen (C, H, O) but with a much lower proportion of oxygen than carbohydrates.

Structure of carbohydrates, proteins, and lipids as large molecules made up from smaller basic units

Carbohydrates are polymers of monosaccharides (e.g., glucose); Proteins are polymers of amino acids; Lipids are made of glycerol and fatty(Punny) acids.

Practical: Investigate food samples for the presence of glucose, starch, protein, and fat

Glucose: Benedict's test (blue to brick-red(hehe im bricked) precipitate on heating); Starch: Iodine test (brown-orange to blue-black); Protein: Biuret test (blue to purple); Fat: Emulsion test (clear to cloudy white emulsion).

Balanced diet

A diet that contains all the necessary nutrients in the correct proportions to maintain health.

Essential nutrients (food substances)

Carbohydrates, proteins, fats, vitamins, minerals, water, and dietary fibre.

Sources and functions of carbohydrates, protein, lipid, vitamins, minerals, water, and dietary fibre

Carbohydrates: Energy source (e.g., bread, pasta); Proteins: Growth, repair, enzymes (e.g., meat, fish); Lipids: Energy storage, insulation, cell membranes (e.g., oils, butter); Vitamins: Various functions, e.g., Vitamin C for healthy skin (e.g., fruits, vegetables); Minerals: Various functions, e.g., Calcium for bones (e.g., milk); Water: Solvent, transport, temperature regulation; Dietary fibre: Aids peristalsis (e.g., fruits, vegetables).

Sources and functions of dietary fibre

Dietary fibre: Aids peristalsis (e.g., fruits, vegetables).

Sources and functions of water

Water: Solvent, transport, temperature regulation;

Sources and functions of minerals

Minerals: Various functions, e.g., Calcium for bones (e.g., my milk);

Sources and functions of vitamins

Vitamins: Various functions, e.g., Vitamin C for healthy skin (e.g., fruits, vegetables - my eggplant);

Sources and functions of protein

Proteins: Growth, repair, enzymes (e.g., my meat, fish

Sources and functions of lipid, vitamins, minerals, water, and dietary fibre

Lipids: Energy storage, insulation, cell membranes (e.g., oils, butter);

Energy requirements

Vary with activity levels, age, and pregnancy (boutot >w<)

Practical: Investigate the energy content in a food sample

Calorimetry experiment where the heat released from burning a food sample is used to heat a known volume of water.

Alimentary canal

The continuous tube from the mouth to the anus (gyatt), including the mouth, oesophagus, stomach, small intestine, large intestine, colon, rectum (sum), and pancreas

Peristalsis

Rhythmic waves of muscular contraction that move food (like my meat) along the alimentary canal.

Digestion of starch

Amylase breaks down starch into maltose (in mouth and small intestine).

Digestion of proteins

Proteases (e.g., pepsin in stomach, trypsin in small intestine) break down proteins into amino acids.

Digestion of lipids

Lipase (in small intestine) breaks down lipids into fatty acids and glycerol. Bile (produced by liver, stored in gall bladder) emulsifies fats, increasing surface area for lipase action.

Role of neutralising stomach acid and emulsifying lipids

Bicarbonate from the pancreas neutralises acidic chyme from the stomach, creating an optimal pH for small intestine enzymes. Bile emulsifies fats for digestion.

Small intestine adaptation for absorption

Villi and microvilli increase the surface area for absorption, thin walls (one cell thick), rich blood supply.