B2 Flashcards
(202 cards)
1
Q
What is diffusion?
A
Diffusion is the movement of particles from an area of high concentration to an area of low concentration.
2
Q
In what type of substances does diffusion occur?
A
Diffusion occurs in gases and liquids where particles are free to move.
3
Q
Does diffusion require energy?
A
No, diffusion is a passive process and does not require energy.
4
Q
Why does diffusion happen?
A
Diffusion happens because particles are always moving randomly and tend to spread out from areas of high concentration to low concentration.
5
Q
How does temperature affect the rate of diffusion?
A
Higher temperatures increase the rate of diffusion because particles move faster at higher temperatures.
6
Q
What is the concentration gradient?
A
The concentration gradient is the difference in concentration between two areas.
7
Q
What effect does the concentration gradient have on diffusion?
A
A steeper concentration gradient increases the rate of diffusion.
8
Q
How does surface area affect diffusion?
A
A larger surface area allows more particles to diffuse at once, increasing the rate of diffusion.
9
Q
Give an example of diffusion in the human body.
A
Oxygen diffusing from the alveoli in the lungs into the blood and carbon dioxide diffusing from the blood into the alveoli.
10
Q
Why is diffusion important in the human body?
A
Diffusion is important for exchanging gases, nutrients, and waste products across cell membranes.
11
Q
What is a partially permeable membrane?
A
A partially permeable membrane allows some substances to pass through but not others.
12
Q
How does particle size affect diffusion?
A
Smaller particles diffuse faster than larger particles.
13
Q
How does the distance over which diffusion occurs affect the rate of diffusion?
A
A shorter distance increases the rate of diffusion, as particles have less space to travel.
14
Q
What role does the cell membrane play in diffusion?
A
The cell membrane controls what enters and exits the cell, allowing small molecules (like oxygen and carbon dioxide) to diffuse through.
15
Q
What types of substances commonly diffuse across cell membranes?
A
Small, non-polar molecules like oxygen and carbon dioxide can easily diffuse across cell membranes.
16
Q
How does diffusion differ from active transport?
A
Diffusion is passive and moves particles from high to low concentration, while active transport requires energy to move particles from low to high concentration.
17
Q
What is osmosis?
A
Osmosis is the movement of water molecules from a region of higher water concentration (dilute solution) to a region of lower water concentration (concentrated solution) through a partially permeable membrane.
18
Q
Does osmosis require energy?
A
No, osmosis is a passive process and does not require energy.
19
Q
What is a partially permeable membrane?
A
A partially permeable membrane allows some substances, like water molecules, to pass through but not others.
20
Q
What is the water potential?
A
Water potential is the potential of water to move from one area to another, with pure water having the highest water potential.
21
Q
In what direction does water move in osmosis?
A
Water moves from an area of high water potential (less solute) to an area of low water potential (more solute).
22
Q
How does the concentration gradient affect osmosis?
A
A steeper concentration gradient results in a faster rate of osmosis.
23
Q
Why is osmosis important in cells?
A
Osmosis helps regulate water balance in cells, which is essential for maintaining cell shape and function.
24
Q
How do cells control osmosis?
A
Cells control osmosis by regulating the concentration of solutes inside and outside the cell, affecting the water potential.
25
What happens to a plant cell in a hypotonic solution?
In a hypotonic solution, water enters the plant cell by osmosis, causing the cell to swell and become turgid. This turgor pressure provides structural support.
26
What is turgor pressure, and why is it important for plant cells?
Turgor pressure is the pressure exerted by the cell contents against the cell wall, which keeps plant cells rigid and supports the plant structure.
27
What happens to a plant cell in a hypertonic solution?
In a hypertonic solution, water leaves the plant cell by osmosis, causing it to shrink and become plasmolyzed, where the cell membrane pulls away from the cell wall.
28
What is plasmolysis in plant cells?
Plasmolysis occurs when a plant cell loses water in a hypertonic solution, causing the cell membrane to detach from the cell wall.
29
What is an isotonic solution’s effect on plant cells?
In an isotonic solution, there is no net movement of water in or out of the plant cell, so it remains in a flaccid (soft) state without turgor pressure.
30
Why is osmosis essential for plant cell health?
Osmosis maintains the turgor pressure needed for structural support, helping plants stay upright and facilitating nutrient transport.
31
What happens to an animal cell in a hypotonic solution?
In a hypotonic solution, water enters the animal cell by osmosis, which can cause the cell to swell and potentially burst, as animal cells lack a cell wall.
32
What is lysis in animal cells?
Lysis occurs when an animal cell takes in too much water in a hypotonic solution and bursts due to lack of a supporting cell wall.
33
What happens to an animal cell in a hypertonic solution?
In a hypertonic solution, water leaves the animal cell by osmosis, causing it to shrink and become crenated (wrinkled).
34
What is crenation in animal cells
Crenation is the shrinking and wrinkling of an animal cell when it loses water in a hypertonic solution.
35
How does an isotonic solution affect animal cells?
In an isotonic solution, there is no net movement of water in or out of the cell, so the animal cell maintains its normal shape and volume.
36
Why is osmosis critical for animal cells?
Osmosis helps regulate water balance in animal cells, which is essential for maintaining cell shape, function, and overall homeostasis.
37
Why does pure water have the highest possible water potential
Pure water has the highest water potential because it contains no solutes, meaning water molecules are free to move without any obstacles.
38
How do plant cells become turgid?
Plant cells become turgid when they absorb water by osmosis. As water enters the cell, it fills the vacuole and pushes the cell membrane against the cell wall. The cell wall prevents the cell from bursting, creating turgor pressure, which makes the cell firm or turgid
39
How does temperature affect the rate of osmosis?
Higher temperatures increase the kinetic energy of water molecules, potentially speeding up osmosis.
40
Why is osmosis important in kidney function?
Osmosis helps regulate water balance in the body by controlling water reabsorption in the kidneys
41
How does surface area affect the rate of osmosis?
A larger surface area allows more water molecules to move through the membrane at once, increasing the rate of osmosis.
42
Why is osmosis important in kidney function?
Osmosis helps regulate water balance in the body by controlling water reabsorption in the kidneys.
43
What is active transport?
Active transport is the movement of particles from an area of low concentration to an area of high concentration, against the concentration gradient, using energy from respiration.
44
Does active transport require energy?
Yes, active transport requires energy in the form of ATP, which is produced during cellular respiration.
45
Why is energy needed for active transport?
Energy is needed because active transport moves particles against their concentration gradient, which cannot happen through passive processes like diffusion.
46
What role do transport proteins play in active transport?
Transport proteins in the cell membrane act as pumps, using energy to move specific molecules across the membrane against the concentration gradient.
47
Give an example of active transport in plants.
In plants, active transport is used to absorb mineral ions like nitrate from the soil into root hair cells, where the concentration of ions is higher than in the soil.
48
Give an example of active transport in animals.
In animals, active transport is used in the small intestine to absorb glucose and amino acids from the gut into the blood, even when their concentrations are higher in the cells lining the gut.
49
How does active transport differ from diffusion?
Active transport moves substances from low to high concentration with energy, while diffusion is a passive process that moves substances from high to low concentration without energy.
50
How does active transport differ from osmosis?
Active transport moves solutes against the concentration gradient with energy, whereas osmosis is the passive movement of water molecules across a partially permeable membrane from high to low water concentration.
51
Why is active transport important in living organisms?
Active transport is essential for absorbing nutrients and ions when they are in lower concentrations outside the cell than inside, supporting functions like nutrient uptake and waste remova
52
Where does the energy for active transport come from?
The energy for active transport comes from ATP, which is generated during cellular respiration in mitochondria.
53
What factors affect the rate of active transport?
Factors include the availability of ATP, the number of transport proteins, and the concentration gradient.
54
Why do cells that carry out active transport have many mitochondria?
Cells that perform active transport have many mitochondria to supply the ATP needed for energy-intensive transport processes.
55
Why can’t ions and large molecules move by diffusion in some cases?
Ions and large molecules often cannot move by diffusion because they may be moving against the concentration gradient, or they may be too large to pass freely through the membrane.
56
What would happen if a cell stopped producing ATP?
Without ATP, active transport processes would stop, leading to a lack of essential nutrients or ion imbalances, which could harm cell function and overall health.
57
What is mitosis?
Mitosis is a type of cell division that produces two genetically identical daughter cells from a single parent cell,
58
What are the main purposes of mitosis?
Mitosis is used for growth, repair of damaged tissues, replacement of worn-out cells, and asexual reproduction in some organisms.
59
In what types of cells does mitosis occur?
Mitosis occurs in somatic (body) cells, not in reproductive (gamete) cells.
60
How many daughter cells are produced in mitosis?
Mitosis produces two daughter cells.
61
Are the daughter cells genetically identical to the parent cell in mitosis?
Yes, the daughter cells are genetically identical to each other and to the parent cell.
62
How many chromosomes are in the daughter cells after mitosis in humans?
Each daughter cell has 46 chromosomes (23 pairs), the same as the original parent cell.
63
What are the main stages of the cell cycle in mitosis?
The main stages are Interphase, Prophase, Metaphase, Anaphase, and Telophase, followed by Cytokinesis.
64
What happens during Interphase?
In Interphase, the cell grows, replicates its DNA, and prepares for mitosis by producing proteins and organelles.
65
Why is DNA replication important in Interphase?
DNA replication ensures that each daughter cell receives a complete set of genetic information identical to the parent cell.
66
What happens during Prophase?
In Prophase, chromosomes condense and become visible, the nuclear membrane begins to break down, and spindle fibers start to form from centrioles.
67
What is the purpose of spindle fibers in mitosis?
Spindle fibers attach to chromosomes and help pull them apart to opposite sides of the cell during Anaphase.
68
What happens during Metaphase?
During Metaphase, chromosomes align at the cell’s equator (the middle of the cell) and attach to spindle fibers by their centromeres.
69
What happens during Anaphase?
In Anaphase, the sister chromatids are pulled apart by the spindle fibers and move to opposite poles of the cell.
70
Why is the separation of chromatids important in Anaphase?
The separation ensures that each daughter cell will receive an identical set of chromosomes.
71
What happens during Telophase?
In Telophase, the separated chromosomes reach the opposite poles, the nuclear membranes reform around each set of chromosomes, and the chromosomes begin to uncoil.
72
What is Cytokinesis?
Cytokinesis is the division of the cytoplasm and organelles, resulting in two separate daughter cells.
73
How does Cytokinesis differ in plant and animal cells?
In animal cells, cytokinesis occurs by the cell membrane pinching inwards to form two cells. In plant cells, a cell plate forms to divide the cell into two.
74
What is cancer, and how does it relate to mitosis?
Cancer is uncontrolled cell division due to mutations affecting genes that regulate the cell cycle, causing abnormal mitosis.
75
How do checkpoints control the cell cycle?
Checkpoints are control mechanisms in the cell cycle that verify whether the processes at each stage have been accurately completed before the cell proceeds to the next stage.
76
What is cell differentiation?
Cell differentiation is the process by which a cell changes to become specialized for a specific function.
77
When does cell differentiation mostly occur in animals?
In animals, most cell differentiation occurs during early development as the organism grows, although some cells continue to differentiate in adults.
78
Do plant cells differentiate throughout the plant’s life?
Yes, unlike animal cells, many plant cells can differentiate throughout the plant’s life, which allows plants to continuously grow and form new structures.
79
What are stem cells?
Stem cells are undifferentiated cells that have the potential to become any type of specialized cell.
80
Where are stem cells found in animals?
In animals, stem cells are found in early embryos (embryonic stem cells) and in certain tissues like bone marrow (adult stem cells).
81
What is the main difference between embryonic and adult stem cells?
Embryonic stem cells can differentiate into nearly any cell type (they are pluripotent), while adult stem cells can usually only become a limited range of cells (they are multipotent).
82
Where are stem cells found in plants?
In plants, stem cells are found in meristems, which are regions of growth at the tips of roots and shoots.
83
What types of cells can plant meristem cells differentiate into?
Plant meristem cells can differentiate into various plant tissues, such as xylem, phloem, leaf, and root cells.
84
How does differentiation affect cell structure?
As cells differentiate, they develop structures and organelles suited to their specific function, like red blood cells developing a biconcave shape for efficient oxygen transport.
85
Give an example of a specialized animal cell and its adaptation
Red blood cells are specialized to carry oxygen; they lack a nucleus to maximize space for hemoglobin and have a biconcave shape for efficient gas exchange.
86
Give an example of a specialized plant cell and its adaptation.
Root hair cells are specialized for absorbing water and minerals; they have an extended surface area for efficient absorption from the soil.
87
Can differentiated cells in animals divide to form new cells?
Most differentiated cells in animals do not divide. Instead, stem cells divide and differentiate to replace damaged or dead cells.
88
What is cell specialization?
Cell specialization refers to the adaptation of a cell to perform a specific function, resulting from the process of differentiation.
89
How does differentiation lead to the formation of tissues and organs?
Differentiated cells with similar functions group together to form tissues, and different tissues combine to create organs, which perform complex functions in the body.
90
What role does gene expression play in differentiation?
During differentiation, certain genes are “switched on” or expressed, while others are “switched off,” resulting in the production of specific proteins that give the cell its specialized structure and function.
91
Can differentiated plant cells return to an undifferentiated state?
Yes, in some cases, differentiated plant cells can return to a less specialized state and re-differentiate, which allows for tissue regeneration and repair.
92
What is totipotency in plant cells?
Totipotency is the ability of a single plant cell to divide and produce all the cell types needed to create a complete organism.
93
What is the potential use of stem cells in medicine?
Stem cells could be used to replace damaged tissues, treat conditions like Parkinson’s, spinal cord injuries, and regenerate organs, due to their ability to differentiate into various cell types.
94
Why is stem cell research sometimes controversial?
The use of embryonic stem cells raises ethical concerns, as it involves the use of early-stage embryos, which some people believe should be protected as potential human life.
95
What is the difference between stem cells and specialized cells?
Stem cells are unspecialized and can differentiate into various cell types, while specialized cells have specific functions and structures suited to particular tasks.
96
What are the two main types of stem cells in animals?
The two main types of stem cells in animals are embryonic stem cells (pluripotent) and adult stem cells (multipotent).
97
What are embryonic stem cells?
Embryonic stem cells are pluripotent cells found in early embryos that can differentiate into almost any type of cell in the body.
98
What are adult stem cells?
Adult stem cells are multipotent cells found in specific tissues (e.g., bone marrow, skin) and can only differentiate into a limited range of cell types related to their tissue of origin.
99
What is the difference between pluripotent and multipotent stem cells?
Pluripotent stem cells (embryonic) can differentiate into any type of cell, while multipotent stem cells (adult) can differentiate into a limited range of cell types related to their tissue or organ.
100
Where are embryonic stem cells found?
Embryonic stem cells are found in the early stages of embryonic development (the blastocyst stage) in animals.
101
Where are adult stem cells found?
Adult stem cells are found in specific tissues, such as bone marrow, skin, muscles, and the liver, throughout an individual’s life.
102
What is the potential of embryonic stem cells in medicine?
Embryonic stem cells can be used in regenerative medicine to treat diseases by replacing damaged tissues or cells, such as in Parkinson’s disease or spinal cord injuries.
103
What is the function of a stem cell?
Stem cells are undifferentiated cells that divide by mitosis to produce specialized cells, which are used by the body for development, growth, and repair.
104
Describe the difference between a stem cell and a specialized cell.
Stem cells are undifferentiated and can develop into different cell types, while specialized cells have specific structures and functions.
105
Where are embryonic stem cells found, and what is their potential?
Embryonic stem cells are found in embryos. They are pluripotent, meaning they can differentiate into almost any cell type needed to form an organism.
106
Where are adult stem cells found, and what can they become?
Adult stem cells are found in body tissues like the brain, bone marrow, skin, and liver. They are multipotent, meaning they can only differentiate into a limited range of cell types related to their tissue of origin.
107
What is a blood stem cell, and what can it differentiate into?
A blood stem cell, or haematopoietic stem cell, can differentiate into red blood cells, white blood cells, and platelets.
108
How do adult stem cells contribute to repair in the body?
Adult stem cells can remain in a non-dividing state for years and are activated by disease or injury to divide and generate cells needed for tissue repair.
109
What are plant meristems, and why are they important?
Meristems are regions in plants where stem cells are found. These cells allow plants to grow continuously throughout their life by producing new cells
110
Where can stem cells be found in plants?
Stem cells in plants are located in root tips, shoot tips, and rings of meristem cells around the stem that make it thicker.
111
How do stem cells in plant meristems differ from other plant cells?
Stem cells in meristems have thin walls, small vacuoles, and no chloroplasts, allowing them to divide and differentiate, unlike other plant cells which have thick, rigid walls and cannot divide.
112
What medical conditions are scientists trying to treat using stem cells?
Scientists are researching ways to use stem cells to treat conditions like Parkinson’s disease and type 1 diabetes.
113
Where are embryonic stem cells used for medical research derived from?
Embryonic stem cells used in medical research are typically taken from embryos that were created through IVF treatment but have not been implanted in the womb.
114
Why might the use of embryonic stem cells be considered ethically controversial?
The use of embryonic stem cells is controversial because obtaining them involves the destruction of embryos, which some people believe should be given moral consideration as potential human life.
115
Give examples of where stem cells are found in animals and their role.
Stem cells are found in tissues like the bone marrow, where they help in producing blood cells and repairing tissue damage.
116
Sperm Cell Specialised
- flagellum ( whips from side to side to propel sperm to ovum)
- lots of mitochondria ( respiration occurs in mitochondria and the reactions of respiration transport from chemical store so that the flagellum can move)
117
Fat Cell Specialised
-They are adapted by having a small layer of cytoplasm surrounding their fat reservoir. They can expand up to 1000 times that is original size as they fill with fat.
- This confuses the store of energy enabling an animal to survive when food are short and also providing insulation
118
Red blood cell specialisation
-bioconcave discs (they are pushed in on both sides to form a bio concave shape which increases the surface area to volume ratio speeding up the diffusion of oxygen into cell and carbon dioxide out of the cell)
-No nucleus (this means the space to contain more Hebog globin molecules)
119
What is surface area to volume ratio?
The surface area per unit volume of an object
120
How to calculate it
surface area of an object is a total of all the exterior areas of the object
The area of one face is 2×2= 4cm^2
there is six faces so 4×6= 24cm^2
The volume is height x width x depth which is 2×2×2=8
so the surface eight racial is 24cm²: 8cm²
121
What adaptations have multicellular organisms developed for exchange surfaces?
They have increased surface area to volume ratios to maximize the rate of diffusion, especially for gases and nutrients.
122
How do alveoli in the lungs aid in gas exchange?
Alveoli provide a large surface area for gas exchange. If laid out flat, all alveoli in the lungs would cover an area the size of half a tennis court.
123
Describe the structure of alveoli and how it aids diffusion.
Alveoli have a large surface area, thin walls (one cell thick), and a rich blood supply, which creates a steep concentration gradient for efficient gas diffusion.
124
What gases are exchanged in the alveoli?
Oxygen moves into the bloodstream by diffusion, while carbon dioxide passes out of the blood into the alveoli to be exhaled.
125
What is the role of ventilation in gas exchange?
Ventilation moves air in and out of the lungs, maintaining a steep diffusion gradient for oxygen and carbon dioxide.
126
What are villi, and where are they located?
Villi are small finger-like projections in the walls of the small intestine that increase the surface area for absorption of digested food molecules.
127
How do villi enhance absorption in the small intestine?
Villi have a large surface area, thin walls for short diffusion distances, and a rich blood supply to maintain a concentration gradient for absorption.
128
What is the function of microvilli on villi?
Microvilli further increase the surface area to volume ratio of each villus, enhancing absorption efficiency in the small intestine.
129
Why don’t simple organisms like Amoeba require a transport system?
They have a large surface area to volume ratio, allowing diffusion to occur efficiently across their body surface.
130
Why are transport systems necessary in larger organisms?
Diffusion alone is too slow over larger distances, so transport systems like the circulatory system carry substances where they are needed in the body.
131
How does the circulatory system function as a transport system in animals?
It transports oxygen, nutrients, and waste products like urea to and from cells, helping maintain homeostasis.
132
What adaptations of the lungs maximize oxygen intake?
The lungs have a large surface area due to alveoli, thin walls for short diffusion distance, and good ventilation and blood supply to maintain a steep diffusion gradient.
133
What is the primary function of the heart?
To pump blood around the body, delivering oxygen and nutrients to cells and removing waste products.
134
Describe the structure of the heart.
The heart has four chambers: two atria (upper chambers) and two ventricles (lower chambers). The left and right sides are separated by the septum.
135
What is the role of valves in the heart?
Valves prevent the backflow of blood, ensuring it flows in one direction through the heart.
136
What are arteries, veins, and capillaries?
Arteries carry blood away from the heart, veins carry blood toward the heart, and capillaries connect arteries and veins, allowing exchange of substances with tissues.
137
What is blood composed of?
Blood is made up of red blood cells, white blood cells, platelets, and plasma.
138
What is the function of red blood cells?
Red blood cells transport oxygen from the lungs to the body tissues and return carbon dioxide to the lungs.
139
Why are white blood cells important?
White blood cells are essential for the immune system, helping to fight infection and disease.
140
What role do platelets play in the blood?
Platelets help with blood clotting, preventing excessive bleeding when injuries occur.
141
What is plasma, and what does it do?
Plasma is the liquid part of blood, transporting nutrients, hormones, and waste products throughout the body.
142
How does the heart ensure that oxygen-rich blood reaches the body tissues?
The left side of the heart pumps oxygenated blood from the lungs through the arteries to the body.
143
What is the function of the right side of the heart?
The right side of the heart pumps deoxygenated blood from the body to the lungs for oxygenation.
144
Explain the term “double circulation.”
Double circulation refers to the separate circuits for blood flow: one circuit pumps blood to the lungs, and the other pumps blood to the rest of the body.
145
What is a common heart condition related to blocked arteries?
Coronary artery disease, which can lead to heart attacks if blood flow to heart muscle is reduced.
146
How does a heart attack occur?
A heart attack happens when the blood supply to part of the heart muscle is blocked, causing tissue damage.
147
What are the two main types of blood vessels that carry blood in and out of the heart?
Arteries carry blood away from the heart, and veins carry blood toward the heart.
148
What are ventricles and why are they important?
Ventricles are the two lower chambers of the heart that pump blood out of the heart to the lungs and the rest of the body.
149
What is the function of the septum in the heart?
The septum separates the left and right sides of the heart, preventing oxygen-rich and oxygen-poor blood from mixing.
150
What are valves, and what is their role in the heart?
Valves are flaps in the heart that prevent the backflow of blood, ensuring one-way circulation through the heart chambers.
151
How does oxygenated blood travel through the heart?
Oxygenated blood from the lungs enters the left atrium, moves to the left ventricle, and is pumped out through the aorta to the body.
152
How does deoxygenated blood travel through the heart
Deoxygenated blood from the body enters the right atrium, moves to the right ventricle, and is pumped out to the lungs via the pulmonary artery.
153
What are the four main components of blood?
Red blood cells, white blood cells, platelets, and plasma.
154
What is the role of red blood cells?
To transport oxygen from the lungs to body cells and carry carbon dioxide back to the lungs.
155
What’s in your blood
1. Red blood cells, small bio concave cells that have no nucleus and contain haemoglobin they carry oxygen.
2. White blood cells, large cells that contain nucleus they fight disease by making antibodies
3. Plasma struggle liquids that blood cells flow in over 90% of plasma is water.
4. Platelets tiny structures that help the blood clot.
156
What does the xylem tissue transport, and where does it go?
Xylem tissue transports water and mineral ions from the roots to the stem, leaves, and flowers.
157
How does the phloem transport materials in a plant?
The phloem transports dissolved sugars and other molecules from the leaves to other areas of the plant, a process called translocation.
158
What is translocation
Translocation is the movement of materials from leaves to other tissues throughout the plant.
159
What is the primary function of xylem tissue?
The primary function of xylem tissue is to transport water and dissolved mineral ions from the roots to the stem, leaves, and flowers
160
What is the primary function of phloem tissue?
The primary function of phloem tissue is to transport dissolved sugars and other organic molecules produced during photosynthesis from the leaves to other parts of the plant.
161
What materials does xylem transport, and in which direction does it move?
Xylem transports water and mineral ions in a one-way flow from the roots to the rest of the plant.
162
What materials does phloem transport, and in which direction does it move?
Phloem transports dissolved sugars and nutrients, moving in a two-way flow to distribute nutrients from sources (like leaves) to sinks (like roots or developing fruits).
163
What type of cells make up xylem tissue?
Xylem tissue is made up of dead cells that form hollow tubes, allowing for the unimpeded flow of water.
164
How are xylem cells adapted for water transport?
Xylem cells are elongated, with no end walls, forming continuous tubes. Their walls are thickened with lignin, providing structural support and making them impermeable.
165
What is lignin, and what role does it play in xylem vessels?
Lignin is a substance that strengthens and thickens xylem cell walls, helping to keep the vessels open and providing structural support to the plant.
166
Why are xylem cell walls impermeable?
Xylem cell walls are impermeable to prevent the loss of water as it travels upward through the plant.
167
What type of cells make up phloem tissue?
Phloem tissue is made of living cells, including sieve tube elements and companion cells.
168
What are sieve plates, and what is their function in phloem tissue?
Sieve plates are small holes in the end walls of phloem cells that allow the flow of dissolved sugars and nutrients between cells.
169
How do companion cells support phloem function?
Companion cells provide metabolic support to sieve tube elements, helping maintain the energy needed for active transport in the phloem.
170
Why are phloem cells considered permeable?
Phloem cells are permeable to allow sugars and nutrients to pass through the sieve plates, facilitating their distribution throughout the plant.
171
how do the vascular bundle provide support?
-In the leaf, they form a network that supports the soft leaf tissue.
-In the stem, they are located around the out edge providing the stem with the strength to resist bending in the breeze
-In the roots they are found in the centre
enabling the root as an anchor
172
What is transpiration?
Transpiration is the process of water loss from a plant’s leaves, primarily through the stomata.
173
What is the transpiration stream?
The transpiration stream is the constant flow of water from the roots, through the xylem, and out through the leaves due to transpiration.
174
How can you demonstrate the movement of water in plants?
You can place a white flower in colored water, and the color will travel up through the plant, showing the path of water transport.
175
How does water enter the xylem in the roots?
Water enters root hairs from the soil by osmosis, then moves through the root cells until it reaches the xylem vessels.
176
What adaptation do root hairs have for water absorption?
Root hairs increase the surface area for water and mineral ion absorption from the soil.
177
How is water lost from leaves during transpiration?
Water evaporates from cells inside the leaf and diffuses out through open stomata as water vapor.
178
What is the function of stomata in transpiration?
Stomata are pores on the leaf surface that allow water vapor to escape, facilitating transpiration.
179
What role do guard cells play in the opening and closing of stomata?
Guard cells control the opening and closing of stomata by changing shape in response to water availability, light, and other factors.
180
What is the purpose of the waxy cuticle on leaves?
The waxy cuticle helps prevent excessive water loss from the surface of the leaves.
181
What happens to guard cells when there is plenty of light and water?
Guard cells take in water, become turgid (swollen), and open the stomata for gas exchange and transpiration.
182
What causes stomata to close, and why is this important?
Stomata close when guard cells lose water and become flaccid, reducing water loss, especially in low light or water-scarce conditions.
183
Why do plants wilt?
Plants wilt when they lose water faster than they can absorb it, leading to reduced cell turgor and drooping leaves.
184
How does the structure of the upper surface of many leaves help prevent water loss?
Many leaves have a thick, waxy cuticle on their upper surface to minimize water loss through evaporation.
185
What effect does water loss in leaves have on the xylem pressure?
Water loss in leaves lowers the pressure in the xylem, causing more water to be pulled up from the roots.
186
How does water move from high to low pressure within the plant?
Water moves up the xylem from areas of high pressure (roots) to areas of low pressure (leaves) due to the transpiration pull created by water loss at the leaves.
187
What environmental conditions are ideal for evaporation?
Hot, dry, and windy days are the best conditions for evaporation.
188
What tool is used to measure the rate of transpiration in a plant?
A potometer.
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How does a potometer work?
A potometer measures how quickly a plant shoot takes up water by tracking the movement of an air bubble in a capillary tube.
190
What is the equation for calculating the rate of transpiration using a potometer?
Rate of movement = distance (mm) / time (s).
191
What happens to the rate of transpiration if light intensity increases?
Transpiration rate increases because stomata open wider to allow more carbon dioxide in for photosynthesis.
192
How does decreased light intensity affect transpiration?
The rate of transpiration decreases as stomata close in low light conditions.
193
How does temperature affect the rate of transpiration?
Higher temperatures increase transpiration by causing water to evaporate faster from leaf cells.
194
What happens to the rate of transpiration if temperature decreases?
The rate of transpiration decreases because water vapor diffuses out more slowly in cooler conditions.
195
How does air movement (wind) influence transpiration?
Wind increases the rate of transpiration by moving water vapor away from the leaf surface, maintaining a concentration gradient
196
What effect does low air movement have on transpiration?
Low air movement slows transpiration as water vapor accumulates near the leaf surface, reducing the gradient.
197
How does humidity impact the rate of transpiration?
High humidity decreases the rate of transpiration by reducing the concentration gradient between the leaf and surrounding air
198
What happens to the rate of transpiration in low humidity?
Transpiration rate increases in low humidity as water vapor diffuses out more easily due to a larger concentration gradient.
199
Why is the rate of transpiration linked to the rate of photosynthesis?
Transpiration provides the water necessary for photosynthesis and helps maintain the transport of mineral ions.
200
In an experiment, how would you compare transpiration rates on a sunny and a cloudy day?
By placing a plant in a potometer under different light conditions and measuring the distance an air bubble travels over a set time.
201
What variables should be recorded to analyze transpiration data?
Temperature, humidity, light intensity, and air movement, as these factors all influence transpiration rate.
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How do you use a potometer to measure the rate of transpiration
1. Take a plant shoot and insert it into the potometer’s capillary tube.
2. Add water to the apparatus until the capillary tube is filled, and an air bubble forms.
3. Observe as water moves into the shoot and evaporates from the leaves, drawing more water up the tube.
4. Measure how fast the air bubble travels along the tube, which indicates the rate of transpiration.
5. Refill and reset the apparatus to repeat measurements under different environmental conditions.
