Plants: Lecture 1 Flashcards
Agriculture has had a huge impact on what?
Humans and their relationships with one another and the world around them.
What is agriculture?
It is the domestication of two main groups: plants (wheats and other grasses) and animals (cattle, goats, chickens, etc.).
Where and when was it invented?
It was invented on a large scale nearly 10000 years ago in multiple locations, the main one being Mesopotamia (Iraq).
What did agriculture allow?
It allowed the formation of permanent villages, towns and cities, as people settled down being able to not have to follow their food.
Other consequences of agriculture?
- Larger families and consequently larger populations
- A diverse economy
- Less cooperation due to new and different responsibilities among ppl.
- Different socioeconomic classes due to cities being formed
- the separation of humans from the rest of pure nature environments
- As time went on, large scale war would be powered by agriculture.
Chocolate (Theobroma cacao) ?
-Chocolate is made from the seeds of the chocolate tree
- Chocolate seeds come from the tree and are used to reproduce
- Each seed becomes a new tree when properly fertilized/planted
Seeds, Flowers and Fruits?
Seeds come from fruit and fruit comes from flowers.
- Each fruit comes from a single flower
Oil for cars?
The oil that is burning in cars (fuel) is extracted from plant seeds.
Rubber (Rubber Tree: Hevea brasiliensis)?
If you scored the bark of a rubber tree, rubbery material would come out, which can be treated and heated to form rubber.
- Originally from Brazil/South America but now in Asia to protect from South American parasites.
- it is now 2/3 synthetic and 1/3 from rubber plantations.
Cotton (Gossypium spp.)?
Cotton that is used for clothing comes from the cell walls of a plant. It is made of cellulose (a very common polymer).
What kind of compounds are drugs?
They are plant’s secondary compounds, meaning that they are not needed for metabolism and used as a defence mechanism instead to protect from bacteria or insects.
- Many drugs are made synthetically now.
Secondary compounds?
Compounds that are not necessary for metabolism, growth, or development.
- There are roughly 200,000 drug compounds estimated to exist.
Quinine?
Found in the bark of the Cinchona tree (Cinchona pubescent & other spp.). They are from South America, but have been introduced widely to the rest of the world.
- It is a treatment for malaria (Europe)
- Other uses include: anemia, muscle spasms, cancer treatment, and bitterness of tonic water.
Caffeine (Coffea arabica)?
The coffee tree makes the beans that we grind into coffee. From Yemen, Ethiopia (originally). They grow from a shrub, to a fruit, to a seed, to the coffee that we produce and drink.
Aspirin?
Aspirin is made of Acetylsalicylic acid. It is used to treat pain, fever, and inflammation and also used as a blood thinner. It comes from/is found in willow species’ from the genus Salix. It comes from the bark and the leaves of the willow tree.
Tetrahydrocannabinol (THC)?
Hashish and Marijuana (Cannabis sativa) are used as a recreational/medicinal drug and comes from the plant’s leaves.
Nicotine (tobacco Nicotiana tabacum)?
An alkaloid substance that comes from the leaves of the tobacco plant.
Opium Poppy (Papaver)?
The origin of medicinal and recreational (hard) drugs such as Opium, Heroin, Morphine, and Codeine.
Taxol (yew: Taxus)?
Taxol is the most used cancer treatment/ anti-cancer drug. The evergreen is the source of the taxol. It helps with chemotherapy treatment for ovarian, breast, and lung cancer.
Importance of plants?
Plants make the oxygen and energy used by other components of terrestrial ecosystems.
How much oxygen is made by land plants?
Land plants make half of the oxygen in the world, the other half being made by photosynthetic marine organisms.
Importance of plants: 6 reasons?
- Energy: food (agriculture)
- Energy: fossil fuels
- Clothing
- Drugs, medicines
- Ecosystem Functioning
- Biodiversity
What is botany?
The study of plants - studying a group of plants.
Branches of botany?
- Evolution
- Ecology (community/population)
- Molecular genetics
- Mathematical modelling
- morphology
- anatomy
- physiology
- cell biology
- systematics
- development
Lobelia cardinalis?
The only member of Lobelia that is red, only pollinated by one bird in the east (Ruby-throated hummingbird).
Why do plants have nectar?
Nectar is produced by plants to make them more attractive to potential pollinators (alongside bright and vibrant colours).
- this is the idea that “the plant is paying the bird.”
Male/Female flowers?
Essentially, the older flowers toward the bottom of the plant are female, meanwhile the younger towards the top are male flowers.
How does pollination occur?
The hummingbird fed on the male flowers first, getting pollen on its head. Then it went to the lower female flowers, spreading the pollen (sperm) on the females and therefore fertilizing them.
What are plastids?
Organelles that used to be free-living cyanobacteria who were then engulfed by a eukaryotic cell to photosynthesize for it.
- Agreement made. Cyanobacteria will be housed and the eukaryote will be able to photosynthesize.
What were the large adaptations that caused the emergence of streptophytes?
- Plastids (1,558 mya)
- Red-green split (1,500 mya)
- Chloro-Strepto split (1000 mya)
What groups do we consider plants?
- chlorophytes (green algae)
- charophytes (green algae)
- embryophytes (land plants)
Plants, Green and Red Algae?
Formed from primary endosymbiosis: prokaryote + eukaryote = eukaryote.
- Nonphotosynthetic eukaryote engulfed a photosynthetic cyanobacterium (now a plastid)
Other Eukaryotes (strange names)
Come from secondary endosymbiosis: eukaryote + eukaryote = eukaryote.
- Nonphotosynthetic eukaryote engulfed a photosynthetic eukaryote (green or red alga).
When did plants split from red algae? What features did they possess?
Plants split from red algae (1500 mya or 1.5 bya)
- both single-cell and multicellular forms in early stages
- inhabits marine environments mainly
- inhabits moist environments near ocean shores
When did plants colonize drier environments? Features?
The colonization o drier environments occurred roughly 500mya.
Adaptations include:
- Cuticles
- Vascular tissue (roots and shoots)
- A relationship with fungi
- Seeds and pollen
Since plants colonized land, how many species have been formed?
Roughly 290,000 species of land plants have been formed.
- Relatively, this is not THAT many species.
When did the earth form?
4550 MYA
When did photosynthesis appear?
Cyanobacteria were engulfed 3500 MYA
The colonization of land by plants occurred when?
The colonization of land by plants, fungi, and animals occurred around 500MYA
When did plants and red algae diverge?
The 1st plastid formed alongside the divergence of plants and red algae roughly 1500 MYA
Features of all plants?
- Starch as main energy-storage molecule
- Chlorophyll b
- Cellulose
- Thylakoids
Starch in plants?
All plants use starch as their main energy-storage molecule. Starch is a polysaccharide (carbohydrate) of glucose residues.
Types of starch & their difference?
There is Amylose and Amylopectin:
Amylose is an unbranched chain of glucose molecules and makes up 20% of starch used
Amylopectin is branched (extra bond) of glucose molecules and makes up 80% of starch in plants.
Why is sugar not used and starch is?
Sugar is not very reactive, easily metabolized, but it holds and absorbs water (BAD).
- Starch is easily broken down, very reactive, and doesn’t absorb water which is good.
Chlorophyll b in plants?
- Chlorophyll a is found in all photosynthetic eukaryotes.
- Chlorophyll b is an accessory pigment and passes energy to chlorophyll a.
- Chlorophyll b absorbs slightly different wavelengths of light
Cellulose in plants?
Almost all cells in plants (not sperm) contain cell walls, which contain cellulose.
What is cellulose?
It is a polysaccharide made of unbranched glucose residues
- it is the most common organic polymer on earth
- cotton is 90% cellulose
- It is used to make paper, rayon and cellophane
What are the ancestors of land plants?
Charophytes are the closest relatives of land plants as both contain nuclear and chloroplast DNA, and their anatomical structure is similar. They are a type of green algae.
- Land plants are not descended from modern charophytes, but share a common ancestor with modern charophytes.
Shared features of charophytes and land plants?
- Cell plate and phragmoplast
- Plasmodesmata
- Sperm structure
- Peroxisome enzymes
- Rose-shaped cellulose synthesizing complexes
- Sporopollenin: durable polymer
What is phragmoplast?
- A unique method of cell division
- Cell plate forms in the middle of the cell and microtubules pull away into two new cells
Plasmodesmata?
Extensions of the cell membrane through pores in the cell wall.
- Allows them to transfer products between the cells.
Sporopollenin?
A durable polymer found in the walls of plant spores and pollen. They are chemically inert: stable and persistent in environments.
- Their main function is to protect cells from disease and desiccation, making the cell impermeable to virus and disease.
Potential Advantages of moving to land?
- Air filters less sunlight than water: more light for photosynthesis
- Air has more CO2 than water: more fuel for photosynthesis
- Early terrestrial habitats lacked pathogens/parasites or predators
- Terrestrial soil is richer in nutrients than aquatic soil
Features of LAND plants?
- Cuticle (waxy covering)
- Multicellular, jacketed sex organs called gametangia
- Embryophyte condition
- Alternation of generations
Multicellular, jacketed sex organs?
Jacketed means that some cells are not reproductive but protective instead.
- There are 2 types of gametangia: those that make eggs or sperm.
What is the male sex organ?
The antheridium is the male sex organ. It is haploid and it produces sperm.
What is the female sex organ?
The archegonium is the female sex organ. It is haploid and produces the egg.
What is the embryophyte condition?
The embryophyte condition is when a zygote is retained in the maternal tissue. The egg is fertilized and stays on the structure where it was made while it develops.
Alternation of generations?
There is a multicellular haploid and diploid component of the sexual life cycle. Sperm and egg are made by the haploid multicellular component.
