3.19 (a) and (b) Screen Capture

3.19a

3.19b

3.18 (a) and (b) Screen Capture

3.18a

3.18b

3.2 Fertilisation

Notes


Fertilisation = "fusion of male and female gamete to produce a zygote that undergoes cell division and develops into an embryo"

1. In both Adult male & Adult female:
-> Each is in terms of a Diploid (2n) (diploid = complete set of chromosomes, 46)
-> Diploids divide in testis to produce gametes (meiosis = sperm and egg)
    -> Diploid (2n) / 2 = Haploid (n)
    -> 23 per sperm/egg

2. Fertilisation = two cells are fused together (Sperm gamete & egg gamete) to form ONE CELL

In human:
-> Haploid (n = 23) + Haploid (n = 23) => Diploid (2n = 46) =  new cell known as ZYGOTE
-> Zygote combination of male and female cells but same no. of cells as adult human

3. Mitosis = cell divides (1-2-4-8-16, etc.), 2n -- mitosis --> 2n ALL CELLS CONTAIN DIPLOID (2n = 46) NUMBER OF CHROMOSOMES
-> Embryo = large collection of diploid cells

*Note: process is true for all sexually reproducing animals, variance in no. of chromosomes

3.9b Female Reproductive System

Notes

*before pregnancy, size of uterus = approx. orange

Ovary = meiosis (production of female gametes = eggs)

Oviducts (fallopian tube) = carries eggs to uterus BUT also location of where feritlisation may occur

*Fertilisation = occurs in oviducts NOT in uterus

Uterus = centre structure, wall of uterus which is a muscle stretches during pregnancy, contracts during birth

Lining of Uterus = develops fertilised eggs --> embryo --> child, placenta implants on wall of uterus

Uterus space = where embryo develops into unborn child, stretches to accommodate growing child

Cervix = where sperm cells from the penis enter, entrance to uterus, where sperm cells make way up to oviducts AND where eggs descend down towards

Vagina = collects sperm cells at top of vagina & allows sperm to enter through the cervix

3.9a Male Reproductive System

Notes


Bladder = stores urine

Testis = carry out meiosis produces gametes (sperm cells)

Epididymus = ('coil tube' system), stores sperm cells

Vas deferens = carry sperm cells to penis during sexual stimulation (during sex tube contracts and pushes sperm to penis)

Prostate = Adds 20% - 30% of volume of semen, contains sugars, alkali (alkali nature may neutralise acidic secretions vagina)

Seminal Vesicles = Adds remaining 70% of volume of semen so sperm can travel, produces sugar based secretion, alkali

*SEMEN = sperm cells + (seminal vesicle & prostate secretions)

Urethra = Runs length of penis, common tube joining R + L testis & vas deferens, exit for urine stored in bladder

Penis = Carry sperm cells into vagina during sexual intercourse

3.12 Amniotic Fluid

Notes


Amniotic fluid: Protects developing embryo, surrounds embryo in uterus space

-> Fluid (protection of developing embryo)
     -> Cannot be compressed, 
     -> Absorbs pressure when squeezed
= Prevents damage to embryo by absorbing forces on uterus wall
= Supports foetus as it cannot support own weight during development (bones = not calcified)

e.g. Trying to kick swiftly in water, but pressure (force) of kick is absorbed, slowing leg down

3.11 Placenta

Notes


Embryo: Unborn child, encompassed by uterus (amniotic fluid filled environment), with placenta on spinal side.

Placenta (provides nutrition to embryo)


-> Grows out of embryo in form of umbilical cord

-> Cord spreads out to form placental structure

-> Placenta grows into wall of uterus (past wall lining)

-> Glucose, amino acids & fats (maternal blood stream) --- crossing at (placenta) ---> embryo's blood stream

-> Efficiency/speed of blood/nutrition transfer:
   -> Large S.A. of placenta
   -> Very thin barrier (distance between) mother and embryo

-> Urea, carbon dioxide (embryo) --- crossing at (placenta) ---> maternal blood stream

** Placenta and placental blood vessels(including p. arteries & p. veins) belong biologically to embryo NOT mother

Mitosis Animations

Mitotic Cell Division

(http://www.youtube.com/watch?v=NR0mdDJMHIQ&feature=related)

The Stages of Mitosis

 (http://www.youtube.com/watch?v=VGV3fv-uZYI)

Mitosis

(http://www.youtube.com/watch?v=ATlUv-AGhEU&feature=related)

3.24c Mitosis (3)

Notes


Process of Mitosis


-------------- START OF MITOSIS ---------------

1. Interphase (resting state) = nucleus visible, but chromosomes are not

2. Prophase = Break down of nuclear membrane (nucleus breaks down)-> chromosome visible as a 'pair of chromatids'

3. Pro-metaphase = Inside cell (no nucleus remains), network of protein molecules (spindle/fibres) extends from one pole of the cell to the other:
-> Pair of chromatids join onto protein fibre in centre (via centromere)

4. Metaphase = Pair of chromatids joined onto protein fibre in 'spindle' via centromere.
-> Chromosomes are arranged in the 'equator' of cell

5. Anaphase = 'spindle' fibre shortens -> splits pair of chromatids in opposite directions

6. Telophase = Two nuclei form at opposite ends of the cell, around the seperated chromatids.

--------------------- END OF MITOSIS -----------------------

(7.) Cyto-Kinesis (not regarded as part of mitosis) = Cell begins to move inward dividing cytoplasm in half -> Membrane fuses across equator = Two cells each containing a chromosome (same as parental cell)

-> Human: 23 pairs undergo mitosis at the same time

(http://www.ba-education.com/dna/mitosis.jpg)

3.24b Mitosis (2)

Notes


Mitosis - creating identical 'daughter' cells requires 'DNA replication'

-> Process: Each chromosome undergoes copying process -> Identical copy with identical genes & alleles
---> Takes place inside nucleus (unobservable) = Interphase of cell cycle

-> Two copies held together by centromere (structure around central region) = referred to as 'pair of chromatids'

3.24a Mitosis (1)

Notes


Mitosis = form of cell division -> growth, by increase in number of cells

Outline
Cell, with nucleus -> Diploid number (2N) number of chromosomes (human 2N = 46 chromosomes/cell)

-> Mitosis = cell divides into two, each with 1 diploid nucleus (identical/'daughter' cells):
  --> same number of chromosomes
  --> same set of chromosomes = same chromosome found in copy nucleus

3.16 DNA and Genetic Information

Notes


Chromosomes -> Gene loci

---> Double helix structure (DNA), interwoven parallel helixes

------> Outside sections = 'sugar phosphate backbone'
------> Inside contains 'base pairs' = Adenine (A) <--> Thymine (T), Cytosine (C) <--> Guanine (G) which hold two sides of the 'backbone' together
------------> Base pairs order (right side of helix structure): GENE
(R) (L)

A  T
C  G
T  A
G  C
A  T
A  T
C  G
C  G
A  T
G  C
C  G

Gene inside nucleus = order of bases & number of bases -> codes for construction of protein in cytoplasm -> organism characteristics

3.14 Recall that a nucleus of a cell contains chromosomes on which genes are located

Notes

Chromosome = genetic information within a cell

Typical cell -> Nucleus -> Chromosomes -> DNA (double helix structure) -> Repeating structure known as 'Gene'

Gene = instructions for construction of a protein which define organism characteristics
-> Different organisms contains different number of chromosomes, humans = 46 per cell.

Chromosomes operate in homologous pairs (X,Y), based upon LENGTH of chromosomes (similar lengths will operate together)
-> Identical genes located at identical postion on the chromosomes - known as the gene loci
   -> 2 versions of each gene for 1 characteristic, known as alleles

3.15 Understand that a gene is a section of a molecule of DNA

Notes


DNA - Deoxyribonucleic acid = Double-helix structure
 ->Nucleus
   --> Gene - carries information (characteristics) of organism, individual genes for:
      ---> Blood group (animal)
      ---> Petal colour (plant)
      ---> Etc.

Nucleus, Gene (genetic information) -- passed to Cytoplasm --> Cytoplasm, Protein
 - Protein controls production of characteristic 


Below (http://publications.nigms.nih.gov/thenewgenetics/images/ch1_dnagenes.jpg)
 -> Diagram of DNA relative to cell structure

3.1 Differences in Sexual and Asexual Reproduction

Notes


Sexual

-> Identifiable: Distinguish between male/female
-> Meiosis (gamete cell division): 1/2 total number of adult chromosomes in gamete cells
-> Produce 'gamete' cells (male - sperm / female - egg)
-> Fertilisation: gamete cells fuse together (male / female cells fuse together - 23 x 2 = 46)
-> Variation: Populations of individual sexually reproducing species show broad amount of variations

Asexual

-> NOT Identifiable
-> Mitosis / binary fission: 20 chromosome cell -- divides --> 20 x 2 chromosome cells
-> NO Gamete cells produced
-> NO Fertilisation: no gamete cells = no cell fusion = no fertilisation
-> Small variations: identical population (clones)


*Question: What factors affect whether a species will be a sexually or asexually reproducing animal? What are the advantages/disadvantages of each method, that lends itself to particular circumstances (e.g. Scarce populations of species in an area, therefore asexual would be more advantageous)?

Process of Dry/Wet Deposition and Locations

Notes


Dry Deposition: Sulphur dioxide bonds with transpired water molecules on SA of leaf, causing the leaves to 'burn'

Wet Deposition: Conventional Acid Rain cycle

In Europe (prevailing wind travels NE)

- Dry deposition, where the sulphur dioxide is carried on wind currents, and is deposited on the top parts of trees in that region.

- Wet deposition, AFTER mountainous regions, where wind currents carrying sulphur dioxide condense, and bond with water molecules and acid rain occurs.

4.14 Enhanced Greenhouse Gases

Notes


GHE brought about by GHG (water vapour, carbon dioxide, methane)
  - Increased gases = increased amount of IR light re-emitted back to Earth, RAISE AVERAGE GLOBAL TEMPERATURE (Global Warming)

Consequences


-> Melting of ice caps in polar region = CLIMATE CHANGE
   - raised sea levels,
   - changing ocean currents
   - changing wind currents

-> Raising ave. global temperature = changes in distribution of biomes (major vegetation ecosytems)
  - polar ice-caps melts
  - Deserts expand
  - Deciduous, coniferous forests would change

4.13 Greenhouse gases

Notes


Human activity (fossil fuels) ---> Increased (CO2, NO2) <-- GHG & SO2


  - Industrial
  - Vehicles
  - Domestic (homes)
  - Farming = cows digest crops, emit methane gas to GHE (9% of gases)
  -Water vapour = clouds are main contributors
  - Refrigeration (CFCs) = absorption of UV light, catalysing breakdown of Ozone layer

4.12 Greenhouse Effect

Notes


a) UV light (sun) - Short wavelength, high energy

b) 50% reflected back out to space (before atmosphere penetration) = due to clouds

c) Absorption on Earth SA = UV light converted and emitted as infrared

d) Infrared light = emitted back towards outer space (Space - as heat)

Greenhouse effect


f) Greenhouse gases - Water vapour, CO4 , CH4


    - d) -- IR hits GHG --> f) =  g) absorbs energy BUT re-emitts in ALL DIRECTIONS (backdown, raising SA temp.).

4.11 Gas Pollution Consequences

Notes


Sulphur dioxide (SO2)


 - Combustion of fossil fuels, coals, oils
      - Factories
      - Vehicles

--> Sulphuric acid (SO2 + H2O) = Acid Rain
     - Vegetation: Leaves 'Burned' , Root system leached of magnesium and calcium = no growth
     - Lakes: Reduces Ph (acidic), brings aluminium ions = Al causes mucus thickening in fish,
fish not able to take in enough oxygen (suffocates)

Carbon monoxide


- Combustion of fossil fuels, coals, oils, with INSUFFICIENT OXYGEN

--> Bonds with Hb in RBC = Carbaminohaemoglobin, blocks Hb from carrying oxygen
   - Reduces oxygen circulation, toxic.

4.7 Energy efficiency

Why is only 10% of energy passed from one trophic level to the next?


- Not all energy available to next consumer...lost in:

   - Consumer's life processes (Respiration)
   - Undigested food (faeces)

e.g. 90kJ of plant's energy used by aphid for above, 10kJ left for next consumer

...Because the 90% is used by the consumer (not producer, e.g. grass) for life processes, and in undigested food.

4.6 Energy & Substances in food chains

Producer


Light E -- Photosynthesis --> Chemical E 

= Organic molecules (Carbohydrates, Proteins, Lipids) - Food to next in-line food chain

---> Substances / matter =  (C, H, O, N) contain ENERGY in bonds are passed through food chain

4.5c Food Pyramids

Pyramids - develops on food chains, to quantify trophic levels


Number (counting) = no. of organisms / trophic level = Easiest

Note: Draw pyramids appropriate to quantity e.g. 1 / 10 the quantity = 1 / 10 the size

---> DISADVANTAGES: Does not accurately represent energy balance within system

Biomass (dry mass only, w/o H2O)

Living material and their weight (g, kg, etc.)

Gives better understanding of mass of matter 

---> Need to dry out organism for calculation = impractical

Energy Transfer - 'ideal' to show energy transfer = Accurate

Represents as an accurate percentile, the reduction of energy at each trophic level
Does not face 'pyramid inversion' problem


---> Time consuming, difficult to research and produce

4.5b Food Webs

Webs - provides better description of ecosystem (than chains)

Ecosystem - community of organism that interact (through feeding)

Advantages of food webs


Allows us to show organisms feeding at different trophic levels:
  
     --> Multiple predators
     --> Multiple prey

= Causes links to form in web

4.5a Food Chains

Chain - flow of matter / energy


Producer ---> 1st Consumer ---> 2nd Consumer ---> 3rd Consumer

CAN

Show 1 organism per 1 trophic level

CANNOT

Show organisms being omnivores
Show organisms feeding at > 2 trophic levels

4.4 Trophic Levels

Trophic - to feed


Example:

Producers


Plants (photosynthesis) - Light energy ---> Chemical energy

Primary consumer

Herbivore - Chemical energy (Plant) ---- digestion changes to -----> Chemical energy (Fly)

Secondary consumer


Carnivore - CE ---> CE

Tertiary consumer


Top carnivore - CE --> CE

--- eventually all levels ---> DEATH

Broken down by 'decomposer' organisms (fungi, bacteria)

---- Recycles complex molecules -----> Nitrates & Phosphates 

4.3 Samplings with Quadrats

Method - to compare populations / to estimate populations


Sample - Random (no bias), using non-human factors e.g. Online, Tables.
               - Representative (large, estimation close enough to true population), 10% of area

Example: Sampling daisy population in field

1. Set up grid system across field (like x,y co-ordinates on graph) - EQUAL sizes

2. Place quadrat in 'random co-ordinates' (see above) given.

NOTE: Place quadrat in top-right hand side of 'co-ordinate'

3. Count population within quadrat (population/area ----> e.g. 10 daisies/1m^2)

4. Average = total sum of population / total amount of quadrat samplings

     --> (4+3+5) / 3 = 12 / 3 = 4 daisies/m^2

4.2 Quadrates

Quadrates = Method of sampling different locations within an ecosystem, to compare respective population sizes.

Sand Dune Ecosystem (for example) --> Community / Habitat, split by fence

--> Grazed (A)
--> Ungrazed (B)

Counting population (Quadrating): Estimate of population size 
    Using squares (1m x 1m)
    Take sample of population using square grid
    Count number of organisms

4.1 Ecosystems

Ecosystem: '' Community of organisms in a habitat ''

     -> Community of Organisms
             Populations of different species & interactions
              - Number of individuals of a particular species
              - Organisms that reproduce to give fertile offspring
              - Feeding (food chain)


     -> Habitat
            Abiotic: non-biological factors
            - Cycle of daylight (photoperiods)
            - Temperature: local/seasonal/annual cycles
            - Rainfall
            - Humidity
            - Slope of land/geology

Fruits and Seeds

3.4 Plant Fertilisation

Notes


Fertilisation

- Germinate (tube grows downward)
   - Species specific, only same pollen can germinate
- Pollen ----- pollen tube (style) ---> Ovule

Formation of seed


1. Fertilisation
       Pollen nucleus + Ovule -------> Zygote -----> Embryonic Plant
2. Coating
       Outside ovule forms seed coat (TESTA)
3. Food Store
       Cotyledons (along with Zygote) - food stores to support plant
4. Fruit        
       Ovary walls thicken (energy used - sugars/proteins) ----> Fruit

Petals and Sepals

Stamen System

Carpal System

3.3b Wind Pollination

Notes


Anther (male), PlantB ----Wind (air)----> Stigma (female), PlantB

Adaptions

1. Pollen = Lightweight Grains
     - Wing Feature to move efficiently through air
2. Anthers = hang clear of basic flower structure
     - Exposed to wind
3. Stigma = Large Surface Area
    - Feather-like structure to 'catch' pollen in wind
    - Exposed to wind

Differences to Insect Pollinated (e.g. Grass, Wind Pollinated)

Waste of energy (no need to attract nectaries)
  - No Colours
  - No Scent
  - No Nectaries

3.3a Insect Pollination

Notes


Cross-Pollination = Transfer of:

Pollen (from anther, containing MALE nuclei), PlantA ---INSECTS--> Stigma (female), PlantB

Plant A


Adaptations to attract insects
    Lure:
     - Coloured Petals
     - Scents
    Reward:
     - Food in nectaries - fructose
     - Pollen (source of protein)

---> Male (Stamen)
       Anther (produces pollen grains)
       Filament (supports anther)

---> Female (Carpal)
       Stigma (pollen lands)
       Style (stigma ---> ovary)
       Ovary (contains eggs - OVULES)

Phototropism example

2.81 Phototropism

Notes

"Describing positive phototropism of stems"

Phototropism = Growth response of plant due to light
   - positive (towards light)

Stems


Uniform (all-direction) light = Stems will grow upwards/forwards in direction

Lateral light source (one side) = Stem will bend in tropism towards light
   - Direction of tropism adaptation (light from right) --> Auxin (plant hormone on left), causes more growth on left, pushing stem to right.

NOTE on Auxin: Causes cells to elongate, not divide

2.80 Geotropism

Notes


Geotropism = Growth response of plant due to gravity

Plant seed (conventional orientation)


Embryonic root will grow downwards - positive geotropism (towards gravity centre)
Embryonic shoot will grow upwards - negative geotropism


Plant seed (on it's side)


Root will still show negative geotropism (turn up)
Shoot will still show positive geotropism (turn down)

2.79 Plant response to stimuli

Notes


1. Stimuli = changes in the environment
       - Temperature
       - Light

2. Receptors detect stimuli
    Receptors ----- plant Hormones/growth regulators (e.g. Auxin) -----> Response

3. Response
       - Growth from stimuli = Tropism
          - Temperature    
          - Light                    = Phototropism
          - Gravity                 = Geotropism
          - Water/Moisture     = Hydrotropism

2.54 Transpiration

Notes


Word equation:
Liquid ---------- Heat (Sunlight) ---->  Gas

Process:
1. Water (osmosis): Root system -> Stem -> Leaf -> Stomatal pores to evaporate
2. Sunlight hits leaf surface;
       - Leftover from photosynthesis absorbed by other cell structures -> Produces Heat
       - Water from xylem: Spongy mesophyll -> Cavity 'above' stomata
          - Where phase change occurs
3. Vapor inside (100% humidity) --- Diffusion ----> Outside environment (h < 100%)

2.53 Uptake of Water

Notes

Roots:
 - Branching increases Surface Area for absorption of water
 - Smallest ends of roots have root hairs - epidermis of root shows extension (hair) of cell wall
    - Increases S.A. for absorption of water

Absorption:
 1 Active transport (against concentration gradient, with energy) of minerals --> Surface     epidermal cells & inside root hair
 2 This encourages water uptake (osmosis), dilute = soil/water -->  concentrated = by
    minerals 'moved' into root hair through active transport.

- Water: From root cortex --> root xylem (by osmosis)