Biology 1 - Kauri Studies

Conditions for Photosynthesis

Sunlight + chlorophyll

Site for Photosynthesis

Chloroplasts

Photosynthesis word equation

carbon dioxide + water - > glucose + oxygen

Purpose of photosynthesis

to make food from sunlight

Leaf - large surface area

to absorb more light

Leaf - thin

short distance for carbon dioxide to diffuse into leaf cells

Leaf - chlorophyll

Absorbs sunlight transfer energy into chemicals

Leaf - vein network

To support the leaf and transport water and sugars

Leaf arrangements

Leaves are arranged so that they do not cut off light from one another more than necessary

Position of Leaves

Leaves can change position throughout the day as the sun moves across the sky

Leaf structure (top to bottom)

Waxy cuticle
Upper epidermis
Palisade mesophyll
Spongy mesophyll
Lower epidermis
Waxy cuticle
Stomata

Waxy Cuticle

Prevents evaporative water loss

Epidermis

protects palisade mesophyll, helps to prevent water loss, single transparent layer permits light to pass into the leaf

Palisade mesophyll

tightly packed layer of cells with large amounts of chlorophyll for absorbing sunlight, main site of photosynthesis

Spongy mesophyll

Irregular in shape and loosely packed, fewer chlorophyll and large air spaces for exchange of CO2 and O2 gases between leaf palisade layer and environment

Stomata + Guard cells

opening and closing of guard cells controls gas exchange and water loss from the leaf

Xylem

transport water and minerals to leaf and provide support

Phloem

transport glucose around the body of the plant

Measuring rate of photosynthesis

bubbles produced per minute

Factors affecting rate of photosynthesis

Light Intensity - rate of photosynthesis increases when the light gets brighter (first linear increase then other factors become limiting and thus the rate of photosynthesis decreases)
Wavelength of light - rates of photosynthesis peak in blue-violet and red parts of the visible spectrum with a much lower rate in green light
CO2 Concentration - rate of photosynthesis increases with increasing CO2 concentration (linear increase until other factors become limiting and the rate of photosynthesis decreases)
Temperature - more heat energy causes more collisions between enzyme and substrate. reaches optimum temperature then gets too high and becomes limiting factor

Osmosis

the movement of water from high-concentration to low concentration through a semi-permeable membrane

Capillary action

when water molecules stick to the walls of the xylem (adhesion) and stick to each other (cohesion), and the transpiration pull cause them to move up the xylem

Transpiration

the evaporation of water off the surface of leaves

Transpiration pull

water transpires from the leaves, creating a suction of water up the xylem of the plant to replace the water being lost by evaporation

Diffusion

movement of particles from a region of high concentration to a region of low concentration. carbon dioxide enters the leaves through simple diffusion

Stratification

pattern which shows vertical layering in a forest ecosystem

Stratification layers (top to bottom)

Emergent layer
Canopy layer
Subcanopy layer
Tree Fern layer
Shrub layer
Ground layer

Stratification environment conditons

Windier in the higher layers than the lower layers
Light intensity decreases as you go down in layers
Quality of light (desirable wavelengths) decreases as you go down

Shade plant leaves

Shade plant leaves are found in the understory and are shaded by plants that exist higher up in the stratified layers of the forest. only exposed to low intensity light. e.g. kawakawa tree

Non-shade plant leaves

Non-shade plant leaves are found in the emergent layer of the forest. exposed to high light intensity from the sun e.g. kauri tree.

Surface area difference shade vs non shade leaves

non shade plant leaves have smaller surface area because they do not need to have a large surface area to absorb light energy as they are exposed to high light intensity. protects them from receiving too much light and water loss.
shade plant leaves have larger surface area because they need as large a surface as possible to absorb as much light as possible because they do not receive high light intensity. Understory is humid and thus water loss by evaporation is less of a problem

Density & Thickness difference shade vs non shade leaves

Non shade plant leaves have dense and thick leaves as they need multiple thick palisade mesophyll layers in order to more efficiently absorb all the available sunlight.

Shade plant leaves have less dense, thin leaves as they receive low intensity light and thus need to allow the light to penetrate into the palisade and spongy mesophyll layers.

Colour difference shade vs non shade leaves

Non shade plant leaves have a light green colour as they have a lower concentration of chlorophyll and chloroplasts in their palisade layers as they already receive enough light for photosynthesis.

Shade plant leaves have a dark green colour as they have a higher concentration of chlorophyll and chloroplasts in order to capture and absorb as much light as possible

Number of stomata difference shade vs non shade leaves

Non shade plant leaves have many stomata as a higher intensity of light means a higher rate of photosynthesis. A higher rate of photosynthesis means they need more stomata in order to allow for more CO2 to diffuse into the leaf and allow more O2 to diffuse out of the leaf.

Shade plant leaves have less stomata as lower light intensity means lower rate of photosynthesis which means they need less CO2 to diffuse into the leaf.

Sporangium

A capsule that contains spores

Spore

Reproductive cell that will grow into a new fungus

Sporangiophore

Raises the sporangium upwards, giving it greater exposure to wind, water, and animals

Hyphae

Feeding structure

Mycellium

Network of hyphae

Fungi nutrition process

Extra-cellular digestion

Extra-cellular digestion

Digestive enzymes are secreted from the hyphae onto the food source. The food source is broken down outside the fungus. The digested food is then absorbed into the fungus

Reason for extra-cellular digestion

Large food molecules are too large to be absorbed and must be broken down into individual building blocks to be absorbed by the fungus

Fungus reproduction

Fungi can reproduce both sexually and asexually

sexual fungi reproduction

Hyphae from two different fungi join together and from a fruiting body called sporangia. Sporangia form spores with a mixture of genetic material from the two parent fungi

Sporangia mature, bursting open and releasing spores

Spores get carried by the wind, water or animals into a new location and then germinate to grow into new fungi

Asexual fungi reproduction

A) hyphae fragmentation where a piece of the hyphae break off and grow into a new fungus

B) producing asexual spores which are genetically identical to the parent fungus

Sexual Reproduction advantage

Sexual reproduction introduces genetic variation which can be essential to the survival of the fungus species when environmental conditions change

Sexual reproduction disadvantage

Slower than asexual reproduction

Asexual reproduction advantage

Faster than sexual reproduction

Asexual reproduction disadvantage

no genetic variation so change in environment may wipe out the whole species

Fungus growth

Fungi grow fastest in humid conditions (moist and warm)

Hyphae carry out cell division which allow the hyphae to extend into new environments

Habitat

place where an organism lives

Niche

an organisms place within the ecosystem. The way it lives, its habitat and its role within community. Includes habitat conditions, relationships, and adaptations

Biotic

living parts of an environment

Abiotic

non-living parts of an environment

Kauri tree habitat

subtropical, needs warm summers, mild winters, and evenly distributed rainfall (13-16^C). Upper north island, northland, Auckland, Waikato, bay of plenty.

Kauri tree stratification

requires high light levels so is in the emergent layer

Kauri & mycorrhiza fungus relationship

mutualistic relationship, mycorrhiza grow in the roots of the kauri and their hyphae extend into the roots. Arbuscles help the fungus and kauri exchange resources.

Kauri provide mycorrhiza with nutrition - up to 20% of glucose production can be given to the mycorrhiza

Mycorrhiza increase absorption of water from the soil for kauri. hyphae from the mycorrhiza are much smaller and finer and grow out the roots of the kauri tree increasing absorption.

Parasitic relationship

one species benefits and the other species is harmed

mutualistic relationship

both species benefit

Kauri dieback disease

a parasite that lives and feeds on the roots of kauri trees. it is an example of oomycetes
Kauri dieback organism feeds on living kauri tree cells through extra-cellular digestion. it breaks down the root system and the xylem of the kauri tree causing it to die. no water means no photosynthesis which means no glucose

Oospores

tough, immobile oomycetes pathogen that can be introduced to a forest through contaminated soil being brought in

Sporangium

Oospores germinate, producing sporangium which release mobile zoospores that swim through moist soil to roots of kauri trees

Zoospores

Zoospores germinate on the roots of kauri producing cysts that grow thread-like hyphae which penetrate into the roots, eventually infecting its vasculature (xylem)

Symptoms of Kauri dieback disease

Bleeding gum - defence response from the kauri
Yellowing of leaves - no more chlorophyll production
Thinning of canopy - leaves die and kauri begins to starve
Dead branches - branches die and the trunk and roots begin to starve and die off

How to stop Kauri dieback disease

Stop the spread of the disease:
feral pigs need to be eradicated
humans need to be kept out of the kauri forests
rahui - temporary ban on an area or resource designed to separate people from the area or prevent them from interacting with a resource
Cleaning stations
disinfectants