Botany
Table of Contents
Living or Non-Living
For as long as is imaginable, nothing was alive in our solar system. Then something odd happened, 3.7 Billion years ago. Little oily blobs, fill of water, started to replicate in the oceans of a firey and wet planet. Here began life, and all life on our planet is descended from these first cells.
The most incredible thing with these first little oily blobs, is that the chemical reaction that caused them to release an infra-red glow, has never been extinguished. Rather, these blobs grew in size, and slit into two. Then grew again and split again. As the numbers of blobs grew, they changed. The chemical reactions changed slightly too. Soon, they were able to use energy from the sun to take carbon needed for their structure directly from the carbon dioxide in the air. They then released the dioxide (molecular oxygen) back into our atmosphere. This filled our air with oxygen. The blobs grew and changed, grew and changed. And the chemical reactions kept them glowing an infra-red glow. This self perpetuating series of chemical reactions, a glow that has not been extinguished in over 3.7 billion years, a spark that can be traced back, through millions of ancestors, a thread that ties all species together. Is now seen in you, when you stand near an infra-red camera.
But how do you define this glow? This energetic, self-propogating, interlinking, combusting, and increasingly intelligent and sometimes sentient lineage, this life?
What is Life, and how is it different to all of the other chemical reactions on our planet?
MRS C GREN = Life
The common aspects of all known life are listed below and are used to classify things as living or non-living. They can be memorized using the acronym MRSCGREN. If something cannot do all of these things, then it is non-living - think of fire, it does some but not all of MRSCGREN
Move
Everything that is alive moves in some way, even plants
Respire
To respire is to turn nutrients into energy.
Sense
Sensing light, gravity, smells, touch
Cell
All living things are either cells, or made of cells
Growth
All living things start small, then grow bigger before reproducing. Things get bigger by taking in atoms, as everything is made from atoms. The most important atom in this process is carbon
Reproduce
Reproduction is the creation of descendants
Excretion
Excretion is to get rid of waste products, like the falling of leaves
Nutrition
All living things take in carbon atoms as part of the basis of their food, as all living things on our planet are carbon based life-forms
How do Organisms MRS C GREN
Micro-organisms
Paramecium are an example of a micro-organism. It is a single Cell organism.
They Move by using the hairs on the outside of their cells, moving the hairs back and forward helps to swim forwards.
They Sense bacteria, and they eat this bacteria and this is how they get their Nutrition.
Once that bacteria has been digested, the atoms enter into the paramecium's cytoplasm. Some of these carbon compounds are connected to oxygen making carbon dioxide. The process of breaking down carbon compounds and combining the carbon with oxygen releases energy from the nutrients. To facilitate this Respiration, oxygen diffuses into the cell straight through the paramecium's cell membrane, likewise, carbon dioxide diffuses straight back out.
Any waste products are Excreted through the paramecium's anal pore.
The cell will Grow in size as it takes in these nutrients, the atoms. Once the paramecium is large enough, it will split in half creating two new paramecium's. This is binary fusion is asexual Reproduction.
Plants
Plants are amazing. They use photosynthesis to pull carbon from the atmosphere into living systems. This process then releases oxygen into the atmosphere for use in aerobic respiration by all other organisms. Plants take in this carbon dioxide as their source of carbon. This is Nutrition for the plant. Then energy for this process of creating their own food comes from the sun. In the Cells that are away from the leaves (and in the cells in the leaves) these carbon based sugars are combined with oxygen reversing the process, recreating carbon dioxide and releasing the sun's energy inside the cells of the plant.
This Respiration occurs all of the time, however it is more noticeable at night-time because the oxygen production by photosynthesis has ended and so it is easier to detect the carbon dioxide being created. Not all of the plants carbons are turned back into carbon dioxide. A lot of the carbon is used to create the structures of the plant - all of the structures of the plant are made from carbon. This intake of carbon from the air is used to build the plant, to Grow the plant.
As the plant grows it Senses light and will grow towards the light. It will also sense gravity, and send its roots in the direction of gravity and its stem in the opposite direction. During the day, many plants will turn their leaves towards light. Because Movement is hard to see in plants, as they move very slowly, time-lapse videos can be used. With the Avocado tree time-lapse, the most interesting movement is actually the flower outside as it moves to follow the sun. But, you can see how the leaves move in response to the sun. The pea plant clip shows the movement of the tendrils as it tries to grab things to climb on. Once the plant is an appropriate size it will create seeds that will end up back in the soil, and from which a new plant will grow.
Often the creation of seeds will involve a flower and pollination, the use of pollination gives the genetic diversity of sexual Reproduction. Like people, the carbon dioxide created in respiration is Excreted directly back into the atmosphere. Other waste products such as nitrogen are used in the plant - where as in humans we release nitrogen waste in urine. However, although the plant is amazing at recycling, it has its limits and any unrecyclable waste products are excreted in 'dying' leaves.
Humans are the most successful mammal on the planet, if we consider the number of continents on which they live, their population numbers and their ability to alter the environment. The human organism is a multi-cellular being. Meaning it is made of multiple Cells. Roughly 30 trillion. Each individual cell will do all of the processes of live individually in order to sustain its life. This individual application of MRSCGREN enables the whole organism to conduct MRSCGREN.
The human male and the human female meet and create a new human, this is sexual Reproduction. The baby Grows into an adult by eating atoms. These atoms come from its food, or Nutrition. Most of these atoms are used in the process of Respiration - the conversion of food into carbon dioxide and water and releasing energy from the food (we often say we are 'burning it off'). The waste carbon dioxide is Excreted by breathing it out.
This breathing it to excrete waste carbon dioxide is conducted by the contraction of intercostal muscles around the ribs and the diaphragm. This muscular Movement expands and contracts the lungs, allowing air to be sucked into the lungs (with oxygen) and pushed back out (with carbon dioxide). Waste nitrogen from broken down amino acids is excreted through urine.
The human organism can Sense if food is good or off through sight, touch and through smell.
SciPad
Pages 118, 119, 120, 121, 122, 123
Cells
Prokaryotes vs Eukaryotes
Prokaryotic Cells
Prokaryotic cells are the first life on our planet - they are bacteria
Everything that is not a bacteria, is a Eukaryote and is either a single Eukaryotic cell or multiple Eukaryotic cells
The easiest way to remember it is that you are a Eukaryote
Eukaryotic Cells
Plant and Animal Cells
If we look at plants and animal cells we see that they a whole lot of things in common. The structures inside the cells are like little organs, as such they are called organelles.
Both plant and animal cells have:
Nucleus - where the DNA is kept
Mitochondria - which turns food into energy (ATP)
Endoplasmic Reticulum - where DNA is read and Proteins are built
Golgi - Where proteins that are sent out of the cell are packaged for sending
Cell membrane - the lipid 'skin' of the cell
Cytoplasm - the watery inside that fills up the cell
Cytoskeleton - provides the structure for the cell
Plant Cells
Plants and animals are very different organisms. As such, their cells do have some significant differences. In some ways a plant cells is more complex, this is because plant cells can make their own food via the process of photosynthesis.
In addition to almost everything that an animal cell has (you can find out what is unique to animal cells in the diagram above), plant cells also have:
Cell wall - as the plant does not have a skeleton, the structure and strength of the plant comes from the contributions of each individual cell - the cell wall is made of cellulose and is very strong
Vacuole - the vacuole fills up with water, like filling up a water balloon inside a paper bag, as the balloon fills up the page also fills up. If the vacuole starts to loose water, the cell will loose that internal pressure and the plant will wilt
Chloroplast - chloroplasts contain chlorophyll. It is in the chloroplast where carbon dioxide and water are combined using energy from the sun to create sugar and oxygen.
Photosynthesis
In the beginning, there was only bacteria...
The early earth had a atmosphere rich in carbon dioxide and nitrogen. And then evolved a photosynthetic bacteria Cyanobacteria, also known as blue-green algae.
These cyanobacteria took in carbon dioxide, kept the carbon and released the dioxide, or O2.
After millions of years more complex eukaryotic cells arose that could eat the smaller bacterial cells. However, something incredible happened. Some oe the cyanobacteria absorbed by a eukaroytoic cells became part of the cell and changed over time to become Chloroplasts. Now these big eukaryotic cells could photosynthesis too, these were the first plant cells and were the algea that was not blue-green algae. These then evolved into all other forms of algae, and indeed evolved into all other plant life...
The process of Photosynthesis
Plants take in Carbon Dioxide (CO2) from the air and Water (H2O) from the soil
Plants use the energy from the sun to break these molecules into their atoms
The O2 from the CO2 leaves the plant as the oxygen that we breath
The C (Carbon) then grabs hold of the HOH to make HCOH - this is a hydrated carbon (drinking water makes you hydrated). A hydrated carbon is also known as a Carbohydrate.
The plant will link 6 of these HCOH's together to make Glucose. The Simplest of the Sugars.
This process 'captures' carbon from the atmosphere.
The Glucose can be stuck together into huge chains called Starch
If these chains have side branches (like a Christmas tree) then you have a very complex carbohydrate that humans cannot digest called cellulose (cellulose is used to make the strong parts of plants (cell walls)). It is cellulose that crunches when you snap a fresh carrot
Plants are amazing. They can take glucose and use it's hydrogens, oxygens and most importantly, its carbons to make amino acids (the building blocks of proteins)
These carbons are super important. We are 60-70% water, the rest of our body is carbon based molecules. Indeed, we are carbon-based life-forms
Thanks Jason and Ivan MHJC '19
Because Plants make their own food, they are called autotrophs
If something needs to eat other things, then they are called heterotrophs
Photosynthesis happens in the Leaf
The plant takes in Water from its roots - this goes to the leaves through a process called Transpiration
The plant takes in Carbon Dioxide through holes on the bottom of the leaf called Stomata
The leaf takes 6 Carbon Dioxide molecules and 6 Water molecules and combines them to make one 6 oxygen molecules and 1 Glucose Molecule
The 6 oxygen molecules then leave the leaf through the stomata
The glucose becomes part of the plant - it might be joined together to make Starch (like in potatoes) or Cellulose (fibre - the thing that makes plants strong)
Chloroplasts - The Organelle for Photosynthesis
If you look at a leaf, you will see that it has a top and a bottom
You can tell this because the top is dark green
The bottom is light green
The top is dark green because it is full of Chloroplasts
Chloroplasts are the place where photosynthesis happens
The bottom of the plant is more spongy and has space for air to move - that is Carbon Dioxide, Oxygen and Water Vapor
A very, very good Youtube clip for this Botany Topic
SciPad
Pages 132, 133
Transpiration
Transpiration is the Transport of Water through the plant.
This process starts in the Roots - which is why we water our pot plants
Water needs to get into the leaves for Photosynthesis
Water also needs to get to the leaves to fill up the Vacuoles, so that the plant is firm and not wilting
The process continues with water climbing up the Xylem like a catepillar
Then the water gets to the leaf, where it evaporates out through the stomata. This causes more water to be pulled into the leaf to replace the water that leaves the leaf
Water gets up to the Leaf through 3 Steps:
1. Osmosis (In through the Roots)
2. Capillary Action (Up the Xylem)
3. Evaporation (Out the Stomata)
- Osmosis
Osmosis is the movement of water from an area of high water concentration, to an area of low water concentration until an equilibrium is reached.
This movement occurs across a semipermeable membrane that allows water to move, but traps bigger molecules.
In the example below, the semi-permeable membrane has holes that can let the little blue balls through, but not the red ones.
There needs to be the same number of blue balls on both sides, so the blue balls move across until the concentration of blue balls is the same on both sides.
Now the number of blue balls is the same on both sides, however, the total number of balls is higher on the red ball side when you add them in, so now the level of liquid is higher
In the example below, a semi-permeable membrane separates two sides of the bent pipe. Water can move through the semi-permeable membrane, but sugar can not. So, water moves to where there is lots of sugar, until there are the same number of water molecules on both sides. But because of all the sugar molecules, the side where there was lots of sugar has a higher total volume than the other side because it is the volume of adding all of the sugar on that side plus the water molecules
2. Capillary Action
Water likes water and water likes surfaces
Water likes water, this is why a water drop is quite big before it falls off the tap
Water likes water, this is why water follows water drops on a glass window when it is raining
Water likes water, this is why very small insects can walk on water - the water surface tension - the water wants to stay together
Water likes surfaces, this is why water spreads out when you spill your water onto your book
Water likes surfaces, this is why when you pour water out of a cup, the cup is still wet - because some of the water has stuck to it
Capillary action combines the two phenomenon
The water sticks to the surface, because it likes surfaces, then other water molecules follow the first, and slowly the water climbs upwards
This only happens when the surfaces are very close - like the paper fibers in a paper towel - or the walls of the xylem
3. Evaporation
Heat from the sun causes the leaf to get warm
This causes the water in the leaf to evaporate
The water evaporates out of the leaf through the Stomata
As it leaves the leaf, water is pulled into the leaf from the xylem to replace it
Recap:Transpiration
Water gets up to the Leaf through 3 Steps
Osmosis (In through the Roots)
Capillary Action (Up the Xylem)
Evaporation (Out the Stomata)
Flower Parts
Stamen = men bit = consists of an Anther, like how a stag has an antler, and a filament
The Anther contains pollen, the filament holds the anther out
The Pistil or Carpel is the female bit
It consists of a sticky stigma, for the pollen to land on.
The long style, through which the pollen tube must grow down through
The Ovary which contains the Ovules.
Once fertilized the Ovules become seeds and the Ovary becomes fruit
To attract pollinators the flower has colorful petals and a nectary. The nectary contains sugary water known as nectar
To protect the flower as it develops in the bud, it has Sepals
A Flowers Purpose
The Flower is the reproductive organ of a plant
The purpose of the flower is to make new plants
The purpose of the flower is reproduction
The Flower has pollen, pollen contains sperm cells
The Ovary contains Ovules - these are the eggs
If the sperm meets the egg then you get an embryo forming inside what becomes a seed. The seed can grow into a new plant - thus propagating that plants genetic lineage
The movement of Pollen from the Anther to the Stigma is Pollination.
To call out to bees and other pollinators, the flower is brightly coloured
Pollination
Pollination
This is the process of moving Pollen from the Anther to the Stigma
To help this, insects and birds are used - they are then called pollinators
For their efforts, the pollinators get sugar filled nectar
The plant signals when its pollen is ready to be transported by the insects, and when the nectar is ready for eating by having brightly colored petals and a smell.
Fertilization
Plant Fertilization
After the birds and the bees
Fertilization is the step after pollination.
For fertilization to occur, the pollen that landed on the stigma during pollination now needs to grow. The steps are listed below:
The sugar on the stigma stimulates the pollen tube to grow - and provides nutrients for this growth
It grows a pollen tube down the style of the other plant
A sperm cell travels down the pollen tube to the ovary, then to the ovule
The sperm leaves the pollen tube and enters the ovule
In the ovule, the sperm cell will meet the female gamete, the egg cell, creating a zygote (a new organism).
The ovule will now develop into the seed
Seed Dispersal
For the plant to colonize the land, the seed must be dispersed to new locations. This is Seed dispersal.
The options are
Wind - like a dandelion or a swan-plant - the seed can float on the wind
Water - like a coconut or a mangrove - the seed can float on the water
Explosive - the seed can be thrown away from the plant by the force of an exploding seed pod - gorse
Animal - by Hook - the seed can be hooked onto the coat or foot pads of an animal and transported until the hook breaks - like prickles in the grass when you run in bare feet (Onehunga weed)
Animal - by Digestive system - the fruit containing the seed can be eaten, and the seed deposited in a lump of manure - like apples, tomatoes, oranges
Whist the ovule becomes the seed, the ovary becomes the fruit
The fruit grows as the seed develops
The fruit ripens as the seed reaches maturity and dormancy
The ripening of the fruit is caused by enzymes that digest the cell walls of within the fruit making it softer. Enzymes also turn starches into sugars making the fruit tastier. As much as 20% of a the mass of a ripe fruit is sugar. The fruit also changes colour to indicate to animals that it is ripe.
Interestingly, for grains such as wheat, rice and corn. The outside layer is actually dry pericarp (wall of the ovary) adhering tightly to the seed.
A ripened edible fruit uses animals to disperse the seeds of the fruit through their droppings
