Nutrients and Gas Requirements Flashcards
Module 3
1
Q
Define an autotroph
A
- An autotroph is an organism that can produce its own food using light, water, CO2, or other chemicals.
- Because they produce their own food, they are sometimes called producers
2
Q
Give some examples of autotrophs.
A
- Plants
- Algae (which live in water and whose larger forms are known as seaweed)
- Phytoplankton (sinh vật phù du)
3
Q
What process occur in autotrophs?
A
- Photosynthesis
- Chemosynthesis - do not use energy from the sun to produce food; instead, they make food using energy from chemical reactions, often combining hydrogen sulfide or methane with oxygen
4
Q
Where to find autotrophs that use chemosynthesis
A
- Extreme environments, where the toxic chemicals needed for oxidation are found (eg. bacteria living in active volcanoes)
- Deep ocean, near hydrothermal vents (i.e. narrow crack in the seafloor).
- Seafloor called cold seeps
5
Q
Outline some materials that autotrophs use in chemosynthesis.
A
- Sulfur (extreme environments)
- Hydrogen sulfide (hydrothermal vents)
- Methane (cold seeps)
6
Q
Most plants are described as vascular plants. A small number of plants are called non-vascular plants (e.g. mosses, …) because they do not possess transport system.
A
Information
7
Q
Outline body system of most vascular plants
A
- Root
- Shoot
- Vascular system
8
Q
Function of vascular system
A
- It involved in the transport of substances in plants
- It is composed of two different types of tissues - Xylem and Phloem
9
Q
What separates phloem and xylem?
A
- The thin membrane called cambium, which is a layer of actively dividing cells that is responsible for the growth of stems and roots.
10
Q
One xylem and one phloem also called
A
Vascular bundle
11
Q
What running the length of leaves, stems, and roots of plant?
A
Multiple vascular bundles
12
Q
Function of xylem
A
- The xylem is responsible for the transport of water, along with water-soluble nutrients and minerals, absorbed from the soil through the root system.
- The xylem is responsible for keeping a plant hydrated.
13
Q
Which way does the xylem sap travel?
A
- Xylem sap travels only upwards and has to overcome serious gravitational forces to deliver water to a plant’s upper extremities.
14
Q
Explain how water transports inside xylem ( transpiration-cohesion-tension theory)
A
- Transpiration occurs because individual water molecules are attracted to one another, called cohesion. The movement of water upwards through the plants is called transpiration.
- Water can move up the xylem, because of a property called adhesion, whereby water is attracted to cell walls of the xylem vessels.
- When the water is lost from the intercellular spaces by transpiration, it is replaced by the water from the surface of the mesophyll cells that surround the intercellular spaces => Increasing surface tension which bring water upwards
15
Q
Describe structure of xylem vessel
A
- Tracheids: long thin cells that are connected together by tapered ends.
- Vessel elements: shorter and wider than tracheids and are connected together end-on-end to form a continuous tube for transports of water. The cell contents die, leaving hollow vessels for the easy flow of water
- Xylem cells are dead, elongated and hollow.
- They have secondary cell walls containing lignin - a compound that creates wood. Lignin in tracheids adds structural support to the xylem and the whole plant (can be spirals, rings or other patterns)
- ‘Pits’ (areas where the secondary cell wall is missing)
- The walls of the vessels are reinforced with lignin, which prevent the vessels from collapsing.
16
Q
Function of phloem
A
- Transports important sugars (in form of dissolved sucrose), organic compounds, and minerals around a plant
- These substances are transported from leaves to non-photosynthesizing parts of plant such as roots and stems)
- Sap within the phloem simply travels by diffusion between cells and works it way from leaves down to the roots with help from gravity
16
Q
Structure of phloem
A
- Phloem is conductive tissue composed of thin-walled cells
- Phloem is made from cells called ‘sieve-tube members’ and ‘companion cells’
- Sieve-tube members: the perforated end walls are called sieve-tube plates (allow the sap to diffuse easily from cell to cell), missing some important structures such as a nucleus, ribosomes and a vacuole.
- Companion cells run adjacent to sieve-tube members and are connected by a number of channels called ‘plasmodesmata’. Companion cells are not lacking in any vital organelles and their nucleus and ribosomes serve both the sieve tube and itself.
16
Q
What is translocation
A
- The distribution process of stored starch, sucrose to all parts of the plant. This process is called translocation.
17
Q
Outline the driving force of substances stream in xylem and phloem
A
- Driving forces in the xylem are transpiration, cohesion between water molecules, adhesion between water and the cell wall, and surface tension.
- Driving force in the phloem is caused by the formation of high and low pressure regions within the phloem tissue
18
Q
Explain Source-Sink Theory
A
- The high-pressure region is in close proximity to where the sucrose is produced and is known as source
- At the source, energy is required to actively pump sugars into the phloem tissue and this creates a very concentrated solution in phloem (also absorb water by osmosis from the nearby xylem tissue) => cause the high-pressure region
- The low-pressure region is where the sucrose is required and is known as sink
- At the sink, which could be roots or other parts that requires nutrients, energy is again required to actively remove the sugars from the phloem. This creates a dilute solution, which causes water to leave the phloem by osmosis and return to the xylem tissue= > caus the low-pressure region
- Difference in pressure between source and sink drives the movement of substances in the phloem. Going from source to sink.
18
Q
Directions of flow in phloem
A
- It depends on where the sink areas of the plant are in relation to the source (leaves)
19
Q
Define stomata
A
- These are pores in the epidermis of leaves which the gases O2 and CO2 move into and out of the plant.
20
Q
Where on leaves can find mostly stomata?
A
- Undersurface of the leaf.
- The upper epidermis may also have some, but there are usually fewer than on the lower epidermis
21
Q
How are stomata arranged?
A
- Australian eucalypts’ leaves have stomata distributed on both surfaces
- Float plant on water usually have stomata only on their upper surfaces, while plants that grow underwater often do not have stomata.
22
Q
What controls the stomatal opening and closing?
A
- The turgor of the guard cells
23
Q
When will the stomata open?
A
- When water flows into the guard cells by osmosis, turgor increases and they expand. Due to the relatively inelastic inner wall, the guard cells bend and draw away from each other.
24
Q
When will the stomata close?
A
- When the guard cells lose water due to osmosis, turgor decreases and shrinks.
25
Q
Which organ is responsible for gas exchange in Animals?
A
- Fish: Gills
- Mammals: Lungs
- Insects: Spiracles
26
Q
Describe the way in which the air enters lungs.
A
- Air enters the lungs through the trachea, which splits into two bronchi and then smaller bronchioles.
- On the bronchioles are alveoli, where gas exchange takes place.
- The alveoli are surrounded by capillaries so gases can diffuse between air and blood.
- Diffusion of O2 and CO2 occurs passively due to the pressure difference across the alveoli and capillary membrane ( areas of high pressure to areas of low pressure).
27
Q
Function of mucus in the trachea and bronchioles
A
Keep the trachea and bronchioles clean and moist.
28
Q
Which condition needed for oxygen can dissolve and then diffuse into blood
A
The alveoli must stay moist
29
Q
Describe the function of the diaphragm which assists the ventilation (thông khí) of lungs.
A
- Diaphragm contracting to draw air in
- Then relaxing to push it out
30
Q
What is tidal ventilation?
A
- It is when air goes in and out the same way.
- This isn’t very efficient because not all of the air that is breathed in with each breath is breathed out again, i.e. some of the air in each breath has already lost its oxygen to the blood. Also, some air from each breath doesn’t make it as far as the gas exchange surface in the alveoli.
30
Q
How marine mammals breath air/ exchange gases?
A
- They also breathe air and must come up to the surface of the water to breathe
- They possess small lungs compared to humans in order to reduce problems of nitrogen building up in the blood caused by diving.
- They have to be able to hold their breaths for long periods of time while diving in order not to get water into their gas exchange system.
31
Q
Advantages of gas exchange system in mammals
A
- They have a circulatory system and the oxygen is absorbed by the blood to be transported to every cell in the body. The size of mammals isn’t limited by their gas exchange system; no matter how big the mammals get, every cell will have a capillary that delivers oxygen.
- The large SA : V ratio of the gas exchange surface. The alveoli in the lungs maximise the Surface Area, allowing more O2 to diffuse at once and increasing the efficiency of gas exchange.
