Biology EOY

Biological molecules, photosynthesis, and organising systems covered

Function of carbohydrates

Provides energy. Found in pasta, rice, and sugar

Function of lipids (fats and oils)

Provides energy, acts as an energy store, and provides insulation. Found in butter and oily fish

Function of proteins

Needed for growth and repair of tissue and to provide energy in case of emergencies. Found in mainly meat and fish but occasionally in beans

Function of vitamin A

Improves vision, keeps skin healthy, and keeps hair healthy. Found in carrots, liver

Function of vitamin C

Needed to prevent scurvy. Found in fruits, especially citruses like oranges

Function of vitamin D

Absorbs calcium and maintains bone health. Found in sunlight, fish, and eggs

Function of calcium (minerals)

Needed to make and strengthen bones and teeth. Found in dairy products

Function of iron

Essential for hemoglobin production and oxygen transport in the blood. Found in red meat, beans, and spinach.

Function of water

Essential for chemical reactions to take place in cells. Found in beverages and foods.

Function of fibre

Provides bulk (roughage) for the intestine to push food through it. Found in whole grains and vegetables

Energy requirement regarding age

Children and teenagers need more energy compared to older people as they need energy to grow and are generally more active

Energy requirement for pregnancy

Pregnant women need more energy than other women as they have to provide energy for their babies to develop alongside them–they practically have to provide energy for two people

Structure or carbohydrates

Made up of simple sugars (monosacharides) like glucose or maltose. Contains carbon, hydrogen, and oxygen (C,H,O)

Structure of proteins

Proteins are made up of amino acids. Contains carbon, nitrogen, hydrogen, and oxygen (C,N,H,O)

Structure of lipids

Lipids are made up of fatty acids and glycerol. Contains carbon, hydrogen, and oxygen (C,H,O)

Test for starch

Add iodine solution to starch. If starch present it becomes blue-black; if not, it stays brown

Test for proteins

Add biuret raegant to the food sample. If protein is present, it turns to purple; if not it will stay blue.

Test for lipids (layers)

Add Sudan III stain solution. If lipids are present, a separate bright red layer will form at the top; if not, the solution stays mixed

Test for lipids (emulsion)

Add ethanol to the solution. If lipids are present, the solution emulsifies and turns cloudy; if not, no lipids are present

Test for glucose

Place test tube with food sample in a hot bath at 75°C for five minutes. Then add drops of Benedict's solution. Leave it for 5 minutes. Concentration of sugar is based on the colour: green/yellow is low concentration, orange is medium concentration, red is high concentration

Enzyme definition

Enzymes are biological catalysts made from protein that break down foods chemically

Lock and key model

Enzymes are specific and only bind with one substrate so only substrates that have a complementary shape to the active site will be broken down by it

Anabolic enzymes

Links together two different substrates

Catabolic enzymes

Breaks down substrates into smaller molecules

Temperature's effect on enzymes

As temperature increases, so does kinetic energy, leading to more enzyme-substrate complexes formed. However, when it is past the optimum, the active site denatures and the substrate can no longer bind to the active site

pH's effects on enzymes

Different enzymes work well at different optimum pH. If the pH is too high or too low, the active site will denature, making substrates unable to bind to the active site

Define denature

When an active site changes shape due to bonds bejng broken

Explain photosynthesis

Plants use chlorophyll to absorb sunlight which acts as a catalyst to convert CO₂ and H₂O into glucose–a plant's source of energy–as well as a waste product of O₂. This process occurs in chloroplasts.

Word equation for photosynthesis

Carbon dioxide + water —> glucose + oxygen

Symbol equation for photosynthesis

6CO₂ + 6H₂O —> C₆H₁₂O₆ +6O₂

Effect of temperature in photosynthesis

Enzymes are involved in photosynthesis so if temperature goes past the optimum, the enzymes’ active sites become denatured and rate of photosynthesis drops

Effect of light in photosynthesis

As light intensity increases, so does the rate of photosynthesis linearly. But after a certain point, light intensity is no longer a limiting factor, something

Effect of CO₂ concentration in photosynthesis

As CO₂ concentration increases, does the rate of photosynthesis linearly. But after a certain point, CO₂ concentration is no longer a limiting factor, something else is

Test light necessity in photosynthesis

1. Deprive plant from light for 48 hours

2. Take leaf from plant and test for starch (iodine)

3. No starch has been made meaning no photosynthesis has occurred: light is necessary

Test chlorophyll necessity in photosynthesis

1. Take variegated (green and white) leaf exposed to light for a bit

2. Test leaf for starch (iodine)

3. Only green parts (parts with chlorophyll) has turned blue-black. Chlorophyll is a necessity

Test CO₂ necessity in photosynthesis

1. Place plant and soda lime (absorbs CO₂) in sealed bell jar with light outside

2. After a while test leaf for starch (iodine)

3. Plant doesn't turn blue-black. CO₂ is necessary

Name leaf structure from top to bottom

Epidermal tissue—>palisade mesophyll tissue—>spongy mesophyll layer

Adaptations of epidermal tissue

• Secretes waxy substance (waxy cuticle)—> protection from water and dirt

• Transparent—> light can go through

• Thin—> easy gas diffusion

Adaptations of palisade mesophyll layer

• at top to maximise sunlight absorption

• packed for as many palisade cells (plant cells) as possible

• many chloroplasts for maximum sun absorption

Adaptations for spongy mesophyll layer

• contains some chloroplasts for photosynthesis

• has space for easy gas diffusion

Adaptations of the stomata

Two guard cells which open up when swollen with water (to let it in) and open during the day when photosynthesis occurs. Typically found at bottom of leaf

Skeletal system

Protects and supports body organs and provides a framework the muscles use to support movement. Made up of bones and joints

Respiratory system

Responsible for exchanging oxygen in and carbon dioxide out through diffusion (gas exchange).

Circulatory system

Pumps blood around the body

Nervous system

The network of nerve cells and fibres that transmits nerve impulses between parts of the body.

Lymphatic system

Composed of a network of vessels, ducts, nodes, and organs. Provides defence against infection.

Digestive system

Breaks down food into absorbable units that enter the blood for distribution to body cells.

Excretory system

Removes waste from your body and controls water balance

Muscular system

Enables movement of the body and internal organs

Why do we have so many different organ systems?

To live we have to carry out all the life processes: nutrition, excretion, movement, sensitivity, growth, reproduction, and respiration. Multiple systems allow complex organisms to carry out different jobs at the same time

Function of liver

Produces bile which breaks down dead blood cells and digests cholesterol (build up may lead to blocked arteries). Also stores glycogen which balances blood sugar levels.

Function of kidney

Regulate the water content in the blood. They excrete/remove the toxic waste products of metabolism (chemical reaction of changing food to energy)

Function of large intestines

Absorbs water and salts from the liquid waste and turns it into solid waste (stool)

Function of small intestines

Digests food further and absorbs nutrients into the blood

Function of lungs

Gas exchange and breathing

Function of stomach

Digests food using peristalsis (mechanical) and enzymes (chemical). Has HCl maintaining pH needed for enzymes to work and kills of bacteria

Function of heart

Pumps blood around the body

Function of brain

Coordinates nervous response

Function of bladder

Stores urine

Function of ciliated cells

Has many tiny hairs called cilia which 'flick' mucus and other materials out the trachea

Function of goblet cell

Produces mucus to trap harmful bacteria and dust. Found in the trachea

Describe the change in the body during inhalation

• diaphragm contracts

• intercostal muscles contract

• volume of ribcage increase

• pressure in chest decreases

• air moves inside lungs.

Describe the change in the body during exhalation

• diaphragm contracts

• intercostal muscles relax

• volume of ribcage decreases

• pressure increases

• air moves out of lungs

Composition of inhaled air

• 21% Oxygen

• 79% Nitrogen

• 0.04% Carbon Dioxide

Composition of exhaled air

• 16% Oxygen

• 79% Nitrogen

• 4% Carbon Dioxide

Word equation for respiration

Glucose + oxygen → carbon dioxide + water + energy (ATP)

Balanced equation for respiration

C₆H₁₂O₆ + 6O2 -> 6CO₂ + 6H₂O

Label the respiratory system

Location of gas exchange

alveoli

Adaptations of alveoli

• Thin walls (just one cell thick) to reduce the diffusion distance

• Large surface area for maximum exchange of gases

• Moist surface for the dissolving of gases in alveolar air so that they can diffuse across the alveolar walls

• Rich blood supply to remove diffused gases and maintain a concentration gradient for further diffusion

Peristalsis

Constriction and relaxation of the muscles of the intestine, trachea, or another canal, pushing digested food forwards

Function of mouth

Food is chewed here to be broken down mechanically. Enzymes begin to break it up the food into smaller molecules chemically

Function of oesophagus

Connects the mouth to the stomach, transporting food and liquids.

Function of rectum

Stores faeces until it is excreted

Function of anus

Muscle which excretes faeces

Villi

Finger-like extensions of the intestinal mucosa that increase the surface area for absorption (taking in nutrients broken down by enzymes)

Heart diagram (unlabelled)

Heart diagram (labeled)

Direction of blood flow

1. Oxygenated blood from lungs to left side of heart

2. Oxygenated blood from heart to rest of body

3. Deoxygenated blood from body to left side of heart

4. Deoxygenated blood from heart to back to lungs

Double circulatory system

Blood passes twice through the heart in one complete cycle, one pump to send blood to the body and the other to pump it back to the lungs. This ensures that the body is never out of supply for oxygen by constantly sending out and obtaining oxygenated blood

Cardiovascular disease

The narrowing/blocking of blood vessels which can lead to a heart attack, chest pain, or stroke

Explain atherosclerosis

When fat cholesterol builds up, the fat dries up and turns into plaque, leading to atherosclerosis, leading to an increase in blood pressure as the heart tries to pump the blood through, possibly leading to a heart attack

Causes of cardiovascular disease

• Genetic variation

• Poor diet—>increases cholesterol and plaque build up

• High blood pressure—>friction narrows and damages vessels, making it more prone to plaque build up

• Smoking—>chemicals from smoking damages vessels, making it more prone to plaque build up

• Sedentary lifestyle—>reduces blood circulation, leading to build up of cholesterol and plaque

• Age—>cholesterol levels naturally increase overtime

Alimentary canal

The passage which food passes through (all the digestive system excluding gallbladder, liver, pancreas, and appendix)

Muscular walls

Contracts (squeeze) and relaxes to send blood throughout your body

Atrioventricular valves

Allows blood to flow from the arteries to the ventricles, but prevent flow in the opposite direction.

Semilunar valves

Allows blood to flow from the ventricles to the arteries and prevent the flow in the opposite direction

Septum

It forms a barrier in the four-chamber of heart, preventing oxygenated and deoxygenated blood from mixing.

Coronary arteries

Supply the heart muscle with blood high in oxygen, branching off the aorta

Function, structure, and width of lumen of arteries

• Carries blood away from the heart

• Thick and strong, containing muscles and elastic tissues

• Lumens are relatively narrow, varying with heart beat due to recoiling and stretching capacity

Function, structure, and width of lumen of veins

• Supplies all cells with their requirements and takes away their waste products

• Very thin; only one cell thick

• Lumens are extremely narrow, wide enough for red blood cells to pass through

Function, structure, and width of lumen of capillaries

• Carries blood towards the heart

• Quite thin, containing smaller amounts of muscles and elastic tissues than arteries

• Lumens are wide, containing valves

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