Weeks 1-2
Section 14.1: Classifying Plants
Non-vascular Plants
Gymnosperm
Monocots
Dicots
- can only reproduce in moist environments as they require the moisture to transport
- plants that do not have vascular tissue
- without vascular tissue to support and transport, they are restricted in size and structure
- minor role in providing food/use for other organisms
- contain vascular tissue that can transport materials within the plant
- the early forms of these organisms are now extinct; only whisk ferns, club mosses, horsetails, and ferns still exist today
- all trees living today are either gymnosperms or angiosperms
Gymnosperm
- the ending of 'sperm' indicates that the organism grows from a seed
- a seed is a complex multicellular structure that contains both an embryo and a food supply
- the seeds of gymnosperms, such as in a conifer, are on the outside of the cone protected by a hard, waterproof coat
- the reproduction through pollen, pollen tubes, and seeds helped gymnosperms survive in cold, dry conditions.
- gymnosperms have evolved to thrive in low nutrient conditions
- plants that grow and develop seeds enclosed in a fruit (also known as flowering plants)
- first flowering plants appeared about 150 million years ago
- more than 75% of plants are angiosperms
- reproduction process mostly includes pollination, relying on other organisms to successfully transfer pollen to other flowers
- angiosperms have evolved to ensure that the exchange of genetic material occurs (in order to avoid self-pollinating)
- angiosperms are divided into two major classes: monocots and dicots
Monocots
- contain only one cotyledon (the 'seed leaves' in the embryo)
- 10% of monocots have tough and rigid stems such as palm and bamboo. These woody monocots grow in warmer climates
- most monocots are herbaceous with soft and fleshy stems; most important among these are the grasses
- animals such as livestock can eat the leaves while humans can only digest the seeds of grasses (because of our enzymes)
Dicots
- contain two cotyledons
- deciduous trees are dicots, contributing $45 billion to Canada's economy
- more common dicots include the lettuce, tomato, cabbage and potato
Section 9.5: Transport in Plants
As the Italian scientist observed, nutrients and water flow through different paths inside the plant. This movement of materials from
one part of the plant to another is called translocation. This process involves two specialized tissues: xylem and phloem.
Xylem
Root Pressure
Plants can build up pressure in the roots that forces the water upward. This is either caused by the cells pumping and secreting water into the xylem (thus increasing pressure) or by the cells frequently transporting ions to cause a change in concentration and therefore cause osmosis. Either way, the collection of water in the xylem tissue forces the water upwards. This method, however, does not work in large plants such as 100 m trees. The amount of force required to create sufficient pressure in order to translocate water through a 100 m tube has never been demonstrated by any tree or plant.
Capillary Action
Some plants have various sized tubes which are connected. When water enters these tubes, it fills up every tube, because they are connected. However, some tubes are extremely narrow and thin, thus resulting the thin ones to fill up more than the rest. Therefore, the amount of water required/force for the water to rise is smaller and allows water and nutrients to be efficiently transported throughout small plants (maximum 90 cm). This method is not viable for plants with larger diameter in tubes and taller plants.
Cohesion-tension
This method differs from the others as it does not force the water upwards. Instead, it pulls the water from above. As stated before, the water in leaves is diffused across the veins. In addition, 99% of the water evaporates into the air through the process of transpiration. As the water molecules evaporate from the leaf, water molecules that are below them in the xylem tissue move upwards to take the place of the evaporated water molecules. This occurs because of the cohesive forces between water molecules. This can also be thought of as the attractive force water molecules have between each other. The process is as follows: the water in the leaf evaporates through transpiration. This causes the molecules that are beneath it in the xylem tissue to be pulled upwards by their attractive force. As a result, the water molecules that are being pulled by the evaporating molecules also pull the water molecules beneath them. This continues until it reaches the xylem tissue in the roots. Then, it starts attracting water from the roots which obtain it from the soil around it.
Conclusion:
The intake and absorption of water and nutrients occurs on different paths of the xylem tissue. However, they are not independent processes. For example, many minerals and some nutrients are absorbed while dissolved in the water by the plant's roots.
Phloem
For transportation to occur in phloem, these observations and parameters must be met:
As the Italian scientist observed, nutrients and water flow through different paths inside the plant. This movement of materials from
one part of the plant to another is called translocation. This process involves two specialized tissues: xylem and phloem.
Xylem
- xylem tissue is formed during the thickening of some plants cells; when xylem cells die, they become a hollow tube which are stacked one on top of another to form a path that extends from the roots to the stem and leaves
- roots take in water through root hairs and epidermal cells by diffusion (osmosis). The water enters the xylem tissue and is then transported into the stem. From the stem, the water in the xylem tissue diffuses to other tissues and in the end the xylem tissue reaches the leaf, where the water is diffused across the whole leaf through the veins visible in the leaf
- There are three major ways a plant can maintain a flow of water/nutrients against the force of gravity. These are:
Root Pressure
Plants can build up pressure in the roots that forces the water upward. This is either caused by the cells pumping and secreting water into the xylem (thus increasing pressure) or by the cells frequently transporting ions to cause a change in concentration and therefore cause osmosis. Either way, the collection of water in the xylem tissue forces the water upwards. This method, however, does not work in large plants such as 100 m trees. The amount of force required to create sufficient pressure in order to translocate water through a 100 m tube has never been demonstrated by any tree or plant.
Capillary Action
Some plants have various sized tubes which are connected. When water enters these tubes, it fills up every tube, because they are connected. However, some tubes are extremely narrow and thin, thus resulting the thin ones to fill up more than the rest. Therefore, the amount of water required/force for the water to rise is smaller and allows water and nutrients to be efficiently transported throughout small plants (maximum 90 cm). This method is not viable for plants with larger diameter in tubes and taller plants.
Cohesion-tension
This method differs from the others as it does not force the water upwards. Instead, it pulls the water from above. As stated before, the water in leaves is diffused across the veins. In addition, 99% of the water evaporates into the air through the process of transpiration. As the water molecules evaporate from the leaf, water molecules that are below them in the xylem tissue move upwards to take the place of the evaporated water molecules. This occurs because of the cohesive forces between water molecules. This can also be thought of as the attractive force water molecules have between each other. The process is as follows: the water in the leaf evaporates through transpiration. This causes the molecules that are beneath it in the xylem tissue to be pulled upwards by their attractive force. As a result, the water molecules that are being pulled by the evaporating molecules also pull the water molecules beneath them. This continues until it reaches the xylem tissue in the roots. Then, it starts attracting water from the roots which obtain it from the soil around it.
Conclusion:
The intake and absorption of water and nutrients occurs on different paths of the xylem tissue. However, they are not independent processes. For example, many minerals and some nutrients are absorbed while dissolved in the water by the plant's roots.
Phloem
For transportation to occur in phloem, these observations and parameters must be met:
- phloem cells must be living
- material can move through phloem in more than one direction at the same time
- phloem can transport large amounts of material very fast throughout the plant
- lack of oxygen and low temperatures both inhibit but do not stop phloem transport
- characteristics of movement inside the plant can differ for every substance
The most accepted theory for transport in phloem is the Mass-flow Theory. In this theory, it is said that the phloem tissue cells have membranes permeable to water. In the leaves, the plant creates sucrose through photosynthesis. Because the membranes of the phloem 'transportation system' are only permeable to water the sucrose is stuck in the leaves. However, when the phloem tissue is submerged in water, the water will want to move into the leaf where the concentration of water is low (by osmosis). By diffusing into the leaf, the water will force out the sucrose into the phloem tissue where it now diffuses evenly across the whole tissue by osmosis as seen in Figure 9.46. Different parts of the plant absorb the sucrose either for food or storage.
Major Plant Tissues
Dermal Tissue System
Dermal Tissue System
- the dermal tissue consists mainly of two parts: the epidermis and the periderm
- the epidermis is the outer layer of the plant and is present in the plant during its primary growth. It produces a layer on the outside of the plant that protects it from excessive water loss, infections by microorganisms, and restricts gaseous exchange.
- as the plant moves into its secondary growth, the epidermis layer is slowly replaced by the periderm. The periderm is similar in that it is the outer most layer and offers protection to the plant. Even when periderm cells die, they still leave a material behind that waterproofs the plant and protects the plant from structural damage
Ground Tissue System
The vascular tissue system made up of mostly xylem and phloem but also has some collenchyma and parenchyma.
Xylem
Plant Organ Systems
The two plant organ systems are the shoot system and the root system.
The shoot system consists of everything above the ground, including the stem, leaves, buds, flowers and fruit. This system is responsible for photosynthesis, storage, as well as part of the transportation. Conversely, the root system consists of everything below the ground and/or any roots that are above the ground. They absorb water and minerals from the earth and are the beginning step into the process of transportation.
- there are three types of ground tissues: parenchyma, collenchyma, and sclerenchyma
- parenchyma is the most common tissue as it is used for processes such as photosynthesis and the storage of nutrients. Plants with a lot of this tissue are called succulents
- ground tissue found in the centre of the roots and stems is called pith and is made up of spongy parenchyma tissue which stores nutrients. In addition, the layer surrounding the pith is called the cortex and is made up of stronger cells
- collenchyma tissue strengthens and offers support to the plant, especially in the primary growth regions. The cells in this tissue have thick but flexible cell walls to allow for strength and flexibility during windy conditions
- sclerenchyma tissue cells have a secondary cell wall used for rigidity. These cells protect and maintain the structure of the plant, even when dead. They can be found scattered, clustered or in a large mass together
The vascular tissue system made up of mostly xylem and phloem but also has some collenchyma and parenchyma.
Xylem
- xylem tissue is the main tissue in plants concerning the transportation of water and minerals
- xylem tissue contains cells called tracheids and vessels
- tracheids are longer and have tapered, overlapping ends. Also, the cell walls have pits which are unthickened areas for more effective material transfer with other cells
- vessels are relatively long with, continuous tubes that are joined end to end and have thickened walls
- tracheids are longer-shaped and have pits in the cell wall that allow for transfer of materials between neighbouring cells
- when vessels and tracheids reach maturity they both die. However, their function still remains as they leave behind lignified cell walls that allow for transport within this xylem tissue. An example of this would be wood, which is almost entirely comprised of xylem tissue
- the phloem tissue is used to transport sugars and other fluids throughout the plant
- opposite to xylem, the phloem is a living tissue when matured
- sieve tubes within the phloem tissue provide a clear pathway for the movement of materials
- these sieve tubes are made of sieve elements, which are long and thin phloem cells with sieve plates at each end
- large pores in the sieve plates allow for easy movement of material
- these cells do not lack many organelles including the nucleus, ribosomes, Golgi apparatus, and vacuoles.
- companion cells serve to direct and supply the sieve tubes with the movement of fluids/material
Plant Organ Systems
The two plant organ systems are the shoot system and the root system.
The shoot system consists of everything above the ground, including the stem, leaves, buds, flowers and fruit. This system is responsible for photosynthesis, storage, as well as part of the transportation. Conversely, the root system consists of everything below the ground and/or any roots that are above the ground. They absorb water and minerals from the earth and are the beginning step into the process of transportation.
In plants, cells divide by mitosis only in specific regions called meristems. These meristems are located in both organ systems at the root tips and shoots tips. They are called apical mersistems. Meristems at other locations along the shoot and root systems are called lateral meristems. A plant first undergoes primary growth. This includes all growth in the length of roots and stems throughout the plant's entire life and the growth in diameter in one year of the roots and plants. The secondary growth is a result of the lateral mersitems that happens throughout the rest of the plant's life. The cells produced by this meristematic tissue will specialize and become all other plant tissues.
Investigation 14A
Procedure:
1/2.
The differences observed in the types of plants shown were typical of every monocot and dicot, respectively. In monocots, the characteristics that seemed to be present in all plants were: veins in leaves parallel, one cotyledon and the flowers were in multiples of threes. Similarly, in dicots they were: two cotyledons, web-like veins in leaves, and flowers in multiples of fours and fives.
4.
1. While it is known internally what differs a monocot from a dicot such as the number of coletydons, the external features are less distinguishable but nonetheless still present. From the pictures seen, one can distinguish whether a plant is monocot or dicot by examining these external features regarding leaves and flower parts.
Leaves + Flower Parts: if the flowers are in multiples of 3 and the leaves have their veins in a parallel pattern they are monocot. If the pattern is web-like and the flower parts are in multiples of 4 and 5, they are dicot.
2. Monocots
Trillium - Ontario
Wild Rose - Alberta
Prairie Crocus - Manitoba
Violet - New Brunswick
Dogwood Tree - British Columbia
Prairie Lily - Saskatchewan
Blue Flag - Quebec
Pitcher Plant - Newfoundland and Labrador
Lady Slipper - Prince Edward Island
Purple Saxifrage - Nunavut
Fireweed - Yukon
Mountain Avens - Northwest Territory
Mayflower - Nova Scotia
3. Seed Leaves Veins in Leaves Flower Parts
Monocots 1 Parallel Multiples of 3
Dicots 2 Web-Like Multiples of 4,5
The most significant of these differences if looking at it anatomically is the seed leaves. This is because the seed is where the whole plant originates from, and the extra cotyledon offers a lot more to the seed as a whole. However, looking at external features I believe the flower parts are the easiest method to distinguish the differences and classify the plant as a dicot or monocot.
4. The monocots and dicots have a shared ancestry, as do all plants. As a result, many features and functions are shared between them. However, according to Darwin's theory, the plants evolved and were selected by nature to survive. This means that many plants adapted to the environment in which they lived in. Thus, it is safe to assume that dicots and monocots that originated from the same environment share similar functions even though anatomically they are different. Even then, there are some functional differences between these two. In my opinion, a big difference is the absence of the secondary growth in the monocots. This means that while it may still grow in length (shoot/arrow meristems) it will not grow in width (lateral meristems). In dicots such as trees, it is clearly visible how thick, tall, and how they continuously add rings as they live. Conversely, in monocots such as bamboo, the lack of lateral growth is evident. The bamboo has no growth rings and while it might be tall, it is not extremely thick.
Therefore, monocots and dicots share a lot of functional features due to their most recent common ancestor. Also, dicots and monocots living in the same environment have adapted to the same environment and likely share the same functions (photosynthesis, growth, etc) even though they might not share the same method of accomplishing that function.
Page 530 q# 1-5
1. The main difference between an angiosperm and a gymnosperm is their seed. The gymnosperm's seed is naked and is located on the outside of a cone in a water proof coat. The angiosperm's seed is encased in a fruit. Gymnosperm: Pine trees, cedar trees, redwood trees, spruce trees, cycad trees
Angiosperm: grasses, vegetables, wild flowers, herds and rice
2. The onion is a monocot. This is because only one leaf emerged from the soil. This shows that the seed (embryo) of the plant contained only one seed leaf (one cotyledon) which clearly means it is a monocot.
3. This has been covered countless times. Onion vs violet
4. Given that two leaves sprouted from one alfalfa seed, it is evident that the plant is a dicot. The seed had two cotyledons, which resulted into the two leaves that sprouted.
5. First determine whether the seed is gymnosperm or angiosperm (was it encased in a fruit?). If it was an angiosperm, then I would proceed to determine if the seed had one cotyledon and was monocot or had two cotyledons and was dicot.
Procedure:
1/2.
- Bean - dicot (2 cotyledons)
- Cauliflower - dicot (2 cotyledons)
- Corn - monocot (1 cotyledon)
- Garlic - monocot (1 cotyledon)
- Onion - monocot (1 cotyledon)
- Pea - monocot (1 cotyledon)
- Tomato - dicot (2 cotyledons)
The differences observed in the types of plants shown were typical of every monocot and dicot, respectively. In monocots, the characteristics that seemed to be present in all plants were: veins in leaves parallel, one cotyledon and the flowers were in multiples of threes. Similarly, in dicots they were: two cotyledons, web-like veins in leaves, and flowers in multiples of fours and fives.
4.
- Trillium - Monocot
Wild Roses - Dicot
Prairie Crocus - Monocot
Violet - Dicot
Dogwood Tree - Monocot
Prairie Lily - Monocot
Blue Flag - Monocot
Pitcher Plant - Dicot
Lady Slipper - Monocot
Purple Saxifrage - Dicot
Fireweed - Dicot
Mountain Avens - Dicot
Mayflower - Monocot
1. While it is known internally what differs a monocot from a dicot such as the number of coletydons, the external features are less distinguishable but nonetheless still present. From the pictures seen, one can distinguish whether a plant is monocot or dicot by examining these external features regarding leaves and flower parts.
Leaves + Flower Parts: if the flowers are in multiples of 3 and the leaves have their veins in a parallel pattern they are monocot. If the pattern is web-like and the flower parts are in multiples of 4 and 5, they are dicot.
2. Monocots
Trillium - Ontario
Wild Rose - Alberta
Prairie Crocus - Manitoba
Violet - New Brunswick
Dogwood Tree - British Columbia
Prairie Lily - Saskatchewan
Blue Flag - Quebec
Pitcher Plant - Newfoundland and Labrador
Lady Slipper - Prince Edward Island
Purple Saxifrage - Nunavut
Fireweed - Yukon
Mountain Avens - Northwest Territory
Mayflower - Nova Scotia
3. Seed Leaves Veins in Leaves Flower Parts
Monocots 1 Parallel Multiples of 3
Dicots 2 Web-Like Multiples of 4,5
The most significant of these differences if looking at it anatomically is the seed leaves. This is because the seed is where the whole plant originates from, and the extra cotyledon offers a lot more to the seed as a whole. However, looking at external features I believe the flower parts are the easiest method to distinguish the differences and classify the plant as a dicot or monocot.
4. The monocots and dicots have a shared ancestry, as do all plants. As a result, many features and functions are shared between them. However, according to Darwin's theory, the plants evolved and were selected by nature to survive. This means that many plants adapted to the environment in which they lived in. Thus, it is safe to assume that dicots and monocots that originated from the same environment share similar functions even though anatomically they are different. Even then, there are some functional differences between these two. In my opinion, a big difference is the absence of the secondary growth in the monocots. This means that while it may still grow in length (shoot/arrow meristems) it will not grow in width (lateral meristems). In dicots such as trees, it is clearly visible how thick, tall, and how they continuously add rings as they live. Conversely, in monocots such as bamboo, the lack of lateral growth is evident. The bamboo has no growth rings and while it might be tall, it is not extremely thick.
Therefore, monocots and dicots share a lot of functional features due to their most recent common ancestor. Also, dicots and monocots living in the same environment have adapted to the same environment and likely share the same functions (photosynthesis, growth, etc) even though they might not share the same method of accomplishing that function.
Page 530 q# 1-5
1. The main difference between an angiosperm and a gymnosperm is their seed. The gymnosperm's seed is naked and is located on the outside of a cone in a water proof coat. The angiosperm's seed is encased in a fruit. Gymnosperm: Pine trees, cedar trees, redwood trees, spruce trees, cycad trees
Angiosperm: grasses, vegetables, wild flowers, herds and rice
2. The onion is a monocot. This is because only one leaf emerged from the soil. This shows that the seed (embryo) of the plant contained only one seed leaf (one cotyledon) which clearly means it is a monocot.
3. This has been covered countless times. Onion vs violet
4. Given that two leaves sprouted from one alfalfa seed, it is evident that the plant is a dicot. The seed had two cotyledons, which resulted into the two leaves that sprouted.
5. First determine whether the seed is gymnosperm or angiosperm (was it encased in a fruit?). If it was an angiosperm, then I would proceed to determine if the seed had one cotyledon and was monocot or had two cotyledons and was dicot.