Bio T4

• Angiosperm 


  Flowering plant
• Endosperm 


  Storage tissue
• Monocotyledons 


  One leaf seeds eg cereal
• Dicotyledon 


  Two seed leaves
• Cotyledons


  Swell to fill seed - get nutrients and food from endosperm and store it
• Brazil Nuts

  No cotyledons - food stored in hypocotyls (developing stalk)
• Seed germination is triggered by imbibition
• Imbibition 


  Special type of diffusion when water is absorbed by solid-colloids causing an enormous increase in volume.
• What is gelatinisation ? 


  Starch granules heated in water and suddenly swell and absorbs water and thicken the liquid
• Starch is also a super-absorbent 


  Starch is cross linked before gelatinised then particles are formed which can be dried. When rehydrated they take up large amounts of water
• Plants are use to :

  Make paper (just fibers of tree)

  Prepare cotton and other natural fibers for clothing

  Harvest wood for building
• High Tensile Strength 


  Makes plants ideal for clothing and packaging as they don’t break easily when pulled
• Advantages of starch foam

  Recyclable

  Biodegradable
• Disadvantages of starch foam

  High temperatures and pressured needed to create - very expensive
• Forming Starch foam 


  (The temperature at which starch gelatinises, depends on amount of water present. Less that 10% = higher temperature required)

  Increase pressure - plastic forms on outside

  Decrease in pressure - seed coat ruptures and steam (expands) forms causing the starch puffs
• Deforestation 


  Cutting down of forest to make land for agriculture, mining, building.

  Wood is renewable because it can be replaced
• Biodegradable 


  Capable of being decomposed by bacteria or other living organisms, therefore avoiding pollution
• Advantages of biodegradable plastics

  Less plastic pollution

  Reduced CO2 admissions
• Disadvantages of biodegradable plastics

  Reinforces a single-use mindset

  Not carbon neutral
• How are seeds adapted for survival

  Protects embryo

  Aid despertion

  Provides nutrients for new plant
• Advantages of Zoos

  Live longer in captivity

  Prevent competition for resources

  Increased population size (breeding programs)

  Maintain health

  Prevents extinction

  Maintain numbers
• Disadvantages of Zoos

  Limited diet

  Climate Change

  Behavioral changes

  Expensive

  Ex situ
• Threats to biodiversity 


  Land development

  Over exploitation

  Introduction of new species

  Pollution
• Aim of Zoos today

  Conservation

  Research

  Education
• Aims of captive breeding programs

  Increase number of individual species

  Maintain genetic diversity (Don’t what homozygous recessive)

  Reintroduce into wild
• Genetic drift

  In small population alleles might not be passed on due to chance - small gene pool.

  Change in allele frequency over time = genetic drift and leads to a reduction in variation
• Inbreeding depression 


  Cause : breeding closely with related individuals (causing homologous genotypes to increase)

  This causes inbreeding depression
• What are Studbooks 


  They show history and location of all animals involved in breeding program for certain species
• What do Studbooks allow 


  Careful selection of mates - genetically different- variety of alleles

  Reintroduction into wild
• In situ 


  Protect it exactly where it is found naturally
• Ex situ 


  Take away and protect else where
• Why are seeds stored, not living plants

  Can be stored in dormant states - no watering/ food/ sunlight

  Less space

  Seeds are produced in lager quantities- collection unlikely to damage wild populations

  More cost effective
• Storage of seeds

  Seeds are stored in cold (reduction on 5 degrees = lifespan doubles)

  Dried to remove water( every 1-2 % water removed = lifespan doubkes)
• Testing for viability 


  Seeds x-rayed - check for fully formed embryos

  Tested periodically - placed in agar and germinated

  Viability is tested every 10 years

  If germinations falls below 75%- plants will be grown and new seed sample collected
• How seeds travel

  Wind

  Animals

  Water

  Bursting

  Humans