Biology Summary Notes (copy)

Unit 1 Characteristics and Classifications of Living Organisms

1.1 Characteristics

MRS. GREN

1.2 Classification

1.3 Features of Organisms

1. Animals: Multicellular, Heterotrophs (energy from other organisms), Most reproduce sexually
2. Plants: Multicellular, Autotrophs (energy from sun)
3. Fungi: Unicellular , Saprotrophs (secreting digestive enzymes onto food outside the body, breaking down the food, absorbing it’s nutrients), Some fungi can be pathogens
4. Protoctists: mainly unicellular, most have nothing to do with humans but some can cause diseases
5. Bacteria: Most feed of off other organisms, live everywhere, some cause diseases
6. Virus: depend on another organism to grow and reproduce, all are pathogens

1. 4 Vertebrates

Divided into 5 groups: fish, amphibians, reptiles, birds, mammals

1.5 Invertebrates

Crustaceans (crabs), myriapods (centipedes), insects (bees), arachnids (spider)

1.6 Ferns and flowering Plants

Unit 2 Organisation of the Organism

2.1 Structure of Cells:

smallest unit of life that can replicate independently

Parts:

Cell membrane: controls which substances can pass in and out of the cell

Nucleus: contains DNA

Cytoplasm: where chemical reactions take place

Mitochondria: provides energy

Ribosomes: site of protein synthesis

Plant cells also have:

Cell wall: support and structure

Vacuole: contains cell sap

Chloroplasts: for photosynthesis (contains chlorophyll)

Microscopy:

Magnification= image size/ object size

2.3 Specialised cells

Specific roles in the body, adapted to fulfil that role

• Ciliated Cell, Root Hair Cell, Xylem Vessels, Neurones, RBC, Palisade Mesophyll cells, Sperm cells, Egg cells

Differentiation: The process that makes cells specialised, changing the shape, structure and combination of organelles.

Stem Cells

1. Divides by mitosis to form more cells
2. Able to differentiate

Zygote→ Mitosis→ embryonic stem cells→ differentiates into any type of cell→ Adult → Has different stem cells that can differentiate into smaller cells (to replace damaged cells)

Plant Stem Cells:

Meristems: Shoots and roots that are growing

2.4 Levels of Organisation in the body

Tissues→ Organs→ Organ systems→ Body

Unit 3 Movement into and out of cells

3.1 Diffusion

Net movement of particles from an area of high concentration to an area of low concentration

Factors:

1. Concentration gradient: larger concentration gradient → higher rate of diffusion
2. Temperature: gives the particle more energy→ they diffuse faster
3. Surface Area: larger→ higher rate of diffusion

3.2 Osmosis

Movement of water molecules across a partially permeable membrane from a region of higher water concentration to lower water concentration

3.4 Active Transport

Movement of water molecules against the concentration gradient from a region of lower concentration to a higher concentration requiring energy from cellular respiration

eg: Root hair cells use active transport to absorb mineral ions→ adaptations : large surface area and lot’s of mitochondria

Unit 4 Biological Molecules

1. Carbohydrates: energy source

2. Lipids (fats, oils): Long term energy store, insulator, protecting organs

3. Proteins: Grow, repair damaged tissue, energy

4. Vitamins: Organic molecules

   1. Vitamin A: leafy vegetables, liver→ good vision, healthy skin and hair
   2. Vitamin C: citrus fruits→ prevents scurvy
   3. Vitamin D: sun, egg→ absorb calcium

5. Minerals: Inorganic molecules

   1. Calcium: milk→strong bones
   2. Iron: red meat, nuts→ anaemia (less RBC)

6. Fibre: helps food move through intestines (prevents diorrhoea, constipation)

7. Water: Needed for chemical reaction, replacing the water lost in the body

4.2 Food Tests

1. Benedict’s test: Reducing sugar

   1. Set 10 drops of Benedict’s solution containing the food water solution and place in water bath for 6 minutes
   2. Safety: Test tube holder, point test tube away from you
   3. Not Present: stays blue
   4. Present: Green→ yellow→ Brick red

2. Iodine Test: Carbohydrate: Iodine Solution

   1. Add Iodine to test tube
   2. Present: blue/black
   3. Not present: Brown/orange

3. Biuret Test: Proteins

   1. 2cm^3 of solution mixed with 2cm^3 Biuret solution
   2. Present: Pink/Purple
   3. Not present: Blue

4. Emulsion Test: Lipids: Ethanol

   1. add 2cm^3 of Ethanol + 2cm^3 of distilled water
   2. Present: Cloudy white colour
   3. Not present: stays the same

5. DCPIP: Vitamin C

   1. add drops of DCPIP into the solution
   2. DCPIP loses its blue black colour when it comes in contact with vitamin C

Unit 5 Enzymes

Speed up the process of chemical reactions

1. Lock and Key model
2. Induced fit: active site changing it’s shape slightly to fit the model

5.2 Factors:

1. Temperature: works best at optimum temperature because too high will change the shape of the active site
2. pH: needs optimum pH else the shape of the active site changes and the substrate will no longer fit

Calculating rate of reaction= How much the product or reactant changes by/ the time it took to change

Unit 6 Plant Nutrition

carbon dioxide + water → glucose + oxygen

6CO2 + 6H20 → C6H12O6 + 6O2

Plant needs: light, chlorophyll, carbon dioxide, water

Product of Photosynthesis: glucose (makes starch and cellulose, converted to amino acid to make protein), oxygen as a by product

Rate of Photosynthesis: Light intensity, temperature, concentration of carbon dioxide

Glasshouse production: gives the ability to control everything the plant needs

Leaves have: large surface area, thin shape, many chloroplast, veins

Palisade Mesophyll: packed tightly to maximise absorption of sunlight, has chloroplasts

Stomata: opens to allow carbon dioxide to diffuse into the cell

Space between the spongy mesophyll so that carbon dioxide can diffuse at all mesophyll cells

Xylem: brings water and ions to mesophyll cells

Open during the day, closed at night

Mineral Requirements: nitrate to make amino acids, magnesium to make chlorophyll

Unit 7 Human Nutrition

7.3 Deficiency Diseases:

Vitamin C: citrus: tissue repair, resistance to disease: bleeding gums (scurvy)

Vitamin D: sun, milk, fish oil: strengthens bones and teeth: rickets, soft bones, osteomalacia

Iron: liver, meat: RBC for O2 transport: tiredness, anaemia

Calcium: milk, fish, green vegetables: strengthens bones and teeth: rickets, muscle weakness, cramps

Digestive Enzymes

Made in Pancreas, Small intestine

Carbohydrates: Starch

• Broken down by Amylase→ to Maltose
• Also made in Salivary Glands

Proteins:

• Broken down by Protease→ Amino acids
• Made in: Stomach (pepsin)

Fats (lipids)

• Broken down by Lipase→ Glycerol

7.5 Teeth

Incisors: biting cutting, Canines: piercing tearing, Premolars, molars: grinding and chewing

Enamel: Hard layer that covers dentine

7.6 Digestive System

To break down the food to be absorbed into the blood

1. Chewing: physical breakdown

2. Saliva: Salivary Amlylase that breaks down carbohydrates, mucus lubricates passage of bolus down the throat

3. Gullet (oesophagus): peristalsis, wave of muscle contractions that squeeze the food down the bolus

4. Stomach: Contracts muscular walls, produces pepsin (breaks down protein), produces hydrochloric acid that kills bacteria

5. Small Intestine: Produces enzymes to aid digestion, food absorbed into the lining of the intestine into the blood stream

   1. Adaptations:

      1. Villi: Finger like projections that increases the surface area of the small intestine so digested food can be absorbed into the blood stream quickly
      2. Villi has only a single layer of surface cells so nutrients have to diffuse a short distance
      3. Good blood supply that maintains the concentration gradient

   2. Pancreas: pushes digestive enzymes (amylase, protease, lipase) into the small intestine in pancreatic juice

   3. Gall Bladder: Releases Bile that neutralises acid in the stomach, emulsifying fats

6. Large Intestine: absorbs excess water

7. Rectum: removal of waste

   

Unit 8 Transport in Plants

8.1 Transport systems

Xylem: transports water and mineral ions from the root to stem to leaf by osmosis

• strengthened by lignin
• Cohesion: water molecules sticking together to move upwards, Adhesion: water molecules sticking to side of xylem vessels reducing the chance that the columns will break

Phloem: transports sucrose made in leaves to other parts of the plant

8.3 Transpiration

Transpiration: evaporation of water at surfaces of mesophyll cells followed by diffusion of water vapour through the stomata into the atmosphere

Measuring transpiration: Potometer

Factors that affect transpiration: light intensity→ increases, temperature and wind speed→ increases, Humidity→ decreases

8.5 Translocation

Movement of sucrose and amino acids from the leaves to regions of respiration, growth, storage (called sinks)

Aphids: insects that feed on sap of phloem by piercing their stylets into the surface of the stem, the pressure of sap in the phloem causes it to pass to the stylet and provide the aphid with food

Unit 9 Transport in Humans

Circulatory System

Double circulation: prevents oxygenated and deoxygenated blood from mixing

The heart:

Pacemaker: in the right atrium causing small electrical impulses to ensure the heart beats properly

Blood Vessels:

Artery:

• carries blood away from the heart
• Strong and elastic muscle tissue
• Arterioles: small subdivisions of arteries

Capillaries:

• exchanges nutrients and oxygen with tissues
• Very small
• Permeable

Vein:

• carries blood to the heart
• Large
• Thin walls with small layers of elastic fibres and smooth muscles
• Has valves which prevents back flow of blood
• Venules: collects blood from capillary beds, unites to form veins

Shunt Vessel:

• Links the artery directly to the vein
• Controls blood flow by constriction and dilation

Blood

RBC:

• Carry oxygen from the lungs to body tissues for cellular respiration
• Has haemoglobin which combines with oxygen to make oxyhaemoglobin
• No Nucleus
• Biconcave disc gives large surface area for oxygen absorption

WBC:

• Phagocytosis: engulf pathogens
• Lymphocytes makes antibodies
  • Antibodies attack by making pathogens stick together (agglutinate), dissolving their cell membranes, neutralising toxins
• Antibodies: bind onto pathogens and help destroy them
• Antitoxins: neutralise any toxins

Platelets:

• Help in blood clotting by thickening the blood and preventing blood from leaving the body and preventing pathogens from entering

Plasma:

• Makes the blood watery so it can flow
• Carries glucose, amino acids, hormones, proteins, urea

9.3 Heart and exercise

Electrocardiogram: traces, pulse rate and sounds of valves closing to monitor heart activity

Physical activity: increases heart rate, increases blood flow to muscles, supplying more oxygen and glucose and removing CO2

9.5 Coronary Heart Disease

Atherosclerosis: cholesterol sticking to the walls narrowing the artery and restricting flow of blood

Thrombosis: rough artery walls causing the blood to clot and block the vessel

Angina: coronary artery gets partially block esp if activity or emotion makes the heart work harder

Heart attack: total blockage, or thrombosis causes heart attack

Cardiac Arrest: heart stops beating

Risk factors: age, sex→ men, genes, smoking

Ways to reduce risk: exercise → makes circulatory system more efficient, Diet→ have saturated fats, less salt, no sugar

Unit 10 Disease and Immunity

Methods of transmission of pathogens: through air, contaminated food and drink, direct contact, indirect contact, insect vectors, body fluid, sexual activity

Defences against disease:

• Mechanical barriers: skin and hairs in the nose
• Chemical barriers: hydrochloric acid, mucus

Blood Defences: phagocytes, lymphocytes

10.2 Defences against disease

• Antibodies lock onto antigens which kill pathogens
• Each pathogen has a specific antigen that fits the shape of the specific antibody
• Active immunity is a defence against a pathogen by antibody production in the body
• Memory cells remember each pathogen so the body becomes immune to the pathogens

10.3 Vaccines

Exposure to pathogens and the immunity the body gets without getting the disease

• Weakened diseases so they are not strong enough to cause a disease, but they still have the same antigens so the body still responds to it and makes antibodies → Immunity!
• Vaccination techniques:
  • Killed organism used
  • Live non virulent strain of the organism used
  • Antigens separated from the organism used
  • Toxin produced by organism may be chemically modified so that it is no longer toxic but still has the same antigens
  • Genetically modified cells
• Pros: Herd Immunity: Control of common diseases, prevents outbreaks even with those who are not vaccinated
• Cons: Don’t always grant full immunity, side effects

10.4 Aspects of Immunity

Passive Immunity: Short term defence against pathogens using antibodies from another individual (breast milk, placenta), no memory cells

Diabetes

Insulin → absorbs excess glucose turning it into glycogen regulating bood glucose

Inability to regulate blood glucose

Type 1

• Pancreas stops producing insulin
• Symptoms: thirst, weight loss, tiredness
• Treatment: Insulin Injections
• Avoid sugary food, exercise regularly

Type 2

• Cells become resistant to insulin
• So the cells don’t take glucose from the blood stream
• Treatment: Healthy, low sugar diet and regular exercise

10.5 Controlling Spread of Disease

Personal Hygiene, Hygienic food preparation, proper waste disposal, sewage treatment, drinking water treatment

Cholera: drinking contaminated food and water causing diarrhoea which leads to loss of ions and water from blood

10.6 Drugs

Drug: substance taken into the body that influences chemical reactions in the body

Antibodies: destroy pathogens

Antibiotics: live inside host cells and take over their metabolic processes

Unit 11 Gas Exchange

Alveolus:

1. Thin so co2 and o2 can diffuse quickly across
2. Moist allows gases to dissolve increasing rate of diffusion, large surface area to volume ratio, permeable, diffusion gradient

• External intercostal muscles raise the ribs, internal intercostal muscles lower the ribs
• Goblet cells: produce mucus which traps dust particles and pathogens in the air and cilia to remove mucus from the airways

Unit 12 Respiration

An exothermic reaction that transfers energy from glucose in all living things

How energy is used:

1. Buildup of larger molecules from smaller ones
2. Muscular contractions
3. Maintaining body temperature

Metabolism: all chemical processes that occur within a living organism in order to maintain life

Aerobic Respiration

Glucose + oxygen → Carbon dioxide + Water

C6H12 + 6O2 → 6CO2 + 6H2O

Takes place when there’s oxygen

Anaerobic Respiration

Glucose → Lactic Acid

• Incomplete breakdown of glucose molecule because no oxygen
• Lactic Acid buildup gives burning sensation in muscles → body gets rid of lactic acid by using oxygen which creates oxygen debt

Fermentation: yeast, plants

Glucose → ethanol + Carbon Dioxide

Exercise and Oxygen Debt

Cellular Respiration→ requires energy→ so rate of breathing and heart rate increases

Excretory System

Kidney

• Filtration of blood and removal of urea

• Regulate the levels of glucose, ions, water

  

Filtration:

Glomerulus absorbing water, glucose, amino acids and urea

Selective Absorption:

Glucose gets reabsorbed

Water based on how much needed

Kidney

1. Remove waste products

2. Regulate the amount of ions

3. Regulate the amount of water in the blood

   

Unit 14 Coordination and Response

Central Nervous system: brain, spinal cord

Peripheral Nervous system: cranial, spinal nerves

<<stimulus→ receptor→ coordinator→ effector→ response<<

14.3 Synapses

• Contains mitochondria and vesicles that contain neurotransmitter molecules
• Uni Directional movement of impulses
• Nuerones don’t touch, the synapses in between them release chemical transmitter substances which triggers an impulse in the second nuerone.

14.4 Eye

Cornea: transparent, light enters through it

Pupil: hole in the centre of the iris, light passes through it

Iris: pigmented, controls the intensity of light entering the pupil

Retina: back of the eye, tissue with sensitive light receptor cells

• Rod cells that work in dim light
• Cone cells detect colour and details

Transparent layer at the front of the eye: provides protection

• Contains tear glands that wash your eye clean every time you blink
• Tears contain lysozyme, that kills bacteria

Ciliary muscles: elastic tissue that can be stretched, changes the thickness of the lens when focusing

Suspensory ligaments: holds the lens in place

Optic nerve: carries nerve impulses to the brain

Pupil Reflex: simple reflex

• Bright light > pupils decrease in size > radial muscles relax and pupil constricts > letting less light into the eyes to protect retina from damage
• No light > pupils increase in size > radial muscles constrict and pupil dilates> letting more light pass into the eye so you can still see

Looking at a distant object:

• Ciliary muscles relax , Pressure inside the eye pulls the suspensory ligaments tight (or taut) so the lens is pulled into an elliptical shape

Looking at a near object:

• Ciliary muscles contract to counteract the pressure inside the eye, Suspensory ligaments becomes slack so the elastic tissue around the lens recoils and the lens becomes spherical

14.6 Hormones

Adrenaline:

• Adrenal Gland
• Increasing breathing rate, pulse rate, widening of pupils
• Increasing oxygen and glucose supply to the muscles

Homeostasis: maintaining the body functions, temperature, pH, CO2, water, O2

Negative feedback:

Pancreas: Makes insulin that decreases blood sugar by turning glucose into glycogen

Makes glucagon that increases blood sugar by turning glycogen into glucose

14.8 Controlling body temperature

Skin: stops pathogens from entering, protects body from damage, prevents too much water loss, detects changes in temperature, detects pressure, loses heat by conduction, convection, radiation, evaporation

Sweating: loses heat

Shivering: Generates heat

Vasoconstriction: narrowing of blood vessels so that the blood moves slowly keeping body warmer and losing less energy, cells use energy for ATP that generates heat

Vasodilation: Blood vessels widen so more energy is transferred to the surroundings by convection and radiation

14.9 Tropic Responses

Gravitropism: response to gravity, roots are positively gravitropic, shoots are negatively gravitropic

Phototropism: response to light, roots are negatively phototropic, shoots are positively gravitropic

Auxins: hormones that control growth, goes on shaded side so that side elongates making plant go in direction of light

Unit 15 Reproduction

15.1 Asexual

• Genetically identical offspring
• Binary Fission, spore production, tuber formation
• produce individuals rapidly, no variation, no resistance to disease, competition of resources

Sexual

• fusion of male and female nuclei to form a zygote producing genetically different offspring
• slow production of individuals, variation, resistance to disease, no competition of resources

15.2 Flower

Insect Pollinated:

• Sepals to protect the flower
• Bright petals
• Stamen has anther and filament
• Each carpel is made of stigma style ovary
• Produces sticky spiky pollen to attract insects

Wind Pollinated

• inconspicous flowers
• feathery stigmas and anthers that hang outside the flower
• light smooth pollen so it can be carried by the wind

15.3 Pollination

Transfer of pollen grains from anther to stigma

Self pollination: transfer of pollen from anther to stigma of same flower, no variation, advantage if there are no insects or plant is growing in isolation

Cross Pollination: transfer of pollen from anther to stigma of a different plant, variation

15.4 Fertilisation

1. Fusion of male and female gamete
2. Pollen tube grows to move the male gamete to the female
3. Fertilised egg grows into embryo inside the ovule which forms a seed

Germinating seeds require: water, oxygen, warm temperature

15.5 Male Reproductive System

testes, scrotum, sperm duct, prostate gland, urethra, penis

Sperm small in size so it can swim to the egg

15.6 Female Reproductive system

Ovaries: make eggs released into oviducts. at ovulation

Oviducts: fertilisation occurs, sperm must reach oviduct

Uterus: organ where embryo develops

Cervix: ring of muscle separating the uterus from the vagina

Zygote→ embryo which implants into the uterus lining

15.8 Pregnancy

• Fetus develops in the uterus
• Umbilical cord attaches fetus to placenta: site of exchange of substances between mother and fetus, acts as barrier for pathogens
• Amniotic fluid: protects fetus from mechanical damage

15.9 Sex Hormones

Testosterone, Oestrogen

15.10 Menstrual Cycle

FSH: development of follicles inside the ovary, secretion of oestrogen

LH: Stimulates ovulation and formation of yellow body from the remains of the follicle

Day 1 to 4: Menstruation

10 days: Uterus lining build up

Day 14: Ovulation

Day 15 to 28: maintaining the uterus lining

Day 28: Menstruation

15.11 STI

• passed via body fluids during sexual contact
• Sharing of needles, unprotected sex, breast milk
• leads to AIDS over time
• destroys lymphocytes that weakens the immune system making body susceptible to many diseases
• ART AntiRetroviral Treatment, zidovudine and other drugs

Unit 16 Inheritance

DNA

A pairs with T

C pairs with G

46 chromosomes→ 23 different types

23rd chromosome- sex chromosome XX XY

Gene: section that codes for a protein

Genome: entire set of genetic material in an organism

Mitosis: produces genetically identical daughter cells

Meiosis: reduction division in which the chromosome is halved from diploid to haploid resulting in genetically different cells

Alleles: different versions of the same gene

Homozygous: 2 of the same allele

Heterozygous: 2 different alleles

Dominant: get expressed

Recessive: doesn’t get expressed when there’s a dominant allele

Genotype: entire collection fo alleles we have

Phenotype: characteristics you get from the genotype

Variation

Natural selection:

Evolution: Inheritance of certain characteristics in a population could lead to changes in a whole species

Mutations

Change in DNA base sequence

Genetic Diagrams

Punnett square

Family Trees

Unit 17 Variation and Selection

Variation: Differences between individuals of the same species

Genetic Variation: Differences in genotype

Phenotypic variation: differences in external and internal appearance

Continuous variation: influenced by genes, environment

Discontinuous variation: small number of phenotypes, no intermediates, caused by genes alone

Natural Selection: only individuals better adapted than others will survive to breed and pass their alleles to offspring

Selective Breeding: humans finding organisms with desirable features, crossing them and selecting the best from the next generation, high yield crops, cattles that produce more milk