Biology final exam Flashcards
1
Q
The ability of one genotype to
produce more than one
phenotype when exposed to
different environments
A
Phenotypic plasticity
2
Q
A plant’s root system changes its shape, size, and depth based on the environment. Ex: It can effect the depth of the root and roots die in areas that lack resources. Some trees have shallow roots due to lack of oxygen
A
Root phenotypic plasticity
3
Q
The segments between nodes
A
Internodes
4
Q
form at nodes above where
leaves attach
bud may grow into
a branch
A
Axillary (or lateral) buds
5
Q
are at the tips of
each stem and branch may also develops into flowers
A
Apical buds
6
Q
Store carbohydrates and starch (potatoes)
A
Tubers
7
Q
Store water has spines (modification of leaves) Ex: Cactus
A
Water- Storage Structures
8
Q
Produce new individuals at nodes above ground (strawberries)
A
Stolons
9
Q
Structure that provides protection from herbivores
A
Thorns
10
Q
Produce new individuals at nodes below ground and store carbs
A
Rhizomes
11
Q
a blade (leaf) and petiole (stalk)
A
simple leaf
12
Q
blade is divided into leaflets
* Needles are adaptations to minimize water loss
A
compound leaf
13
Q
a small surface area,
reducing water loss in areas of the body
where light is abundant
A
Sun leaves
14
Q
large and broad,
providing a high surface area to
maximize photon absorption
Grown
in shade Grown
in sun
A
Shade leaves
15
Q
Plant cells are surrounded by a cellulose-rich
A
primary cell wall
16
Q
a rigid plant cell some plants have
A
secondary cell wall
17
Q
Plant cells are connected by
A
plasmodesmata
18
Q
How many tissue systems do plants have
A
- a)Dermal tissue system b)Ground tissue system c) Vascular tissue system
19
Q
secrete a waxy cuticle to reduce water loss
and protect against pathogens
A
Epidermal cells
20
Q
regulate gas exchange and water loss
* Surrounded by guard cells which change shape to open and close
A
Stomata
21
Q
Hairlike made of epidermal cells
A
trichomes
22
Q
Reflect sunlight to cool the plant’s surface
* Reduce water loss by limiting transpiration
* Barbs or toxins protect against herbivores
* Trap and digest insects
A
Functions of Trichomes
23
Q
Simple tissue
(contains one type of cells)
* thin primary cell walls
* The most abundant and versatile plant
cells
* tissue is the
primary site of photosynthesis (leaves)
* In roots, cells store starch
granules
A
Parenchyma
24
Q
is a simple tissue that provides support
to shoots
* Cells have unevenly thickened primary
cell walls
* Provide flexible structural support to actively growing parts of the plant
* Often found just under the epidermis of stems, especially outside vascular bundles
A
Collenchyma
25
Sclerenchyma vs. collenchyma cells
Sclerenchyma cells are dead at maturity;
provide support after growth has stopped
* Collenchyma cells have expandable
primary cell walls; alive at maturity
26
A thick, rigid secondary cell wall
* Made of lignin and cellulose
Sclerenchyma
27
a complex tissue made
of two types of support cells: Elongated fibers
2. Short sclereids with variable shapes
Sclerenchyma
28
Conducts water and dissolved nutrients from the
root system to the shoot system
Xylem
29
1. Tracheids with pits through which water moves
2. Angiosperms have vessel elements with perforations for
water transport
two types of xylem cells
30
2 parts of Primary growth
Meristems and Apical meristems
31
A compound
leaf has a blade
divided into
leaflets
Opposite leaves
31
A doubly
compound leaf
is large yet
rarely damaged
by wind or rain
Whorled leaves
32
Needlelike leaves
are
characteristic of
species adapted to
very cold or hot
climates
Rosette
33
Alternate sides:
Opposite each
other in pairs
A whorl
Rosettes made by
reducing the
distance between
nodes
Variation in leaf
arrangement:
34
Examples of Modified leaves
Onion bulbs store nutrients
* Succulent leaves store water
* Tendrils enable vines to climb
* The bright red leaves of poinsettias
attract pollinators
* Pitcher plant leaves trap insects
* Cactus spines protect the stem
35
Plant cells
Cell wall
Vacuole
Chloroplasts
Plasmodesmata
36
Cell Wall 🧱
A strong outer layer that gives the cell shape and protection.
Made of cellulose, which is like a tough, plant-based fiber.
Some plant cells have a secondary cell wall for extra strength.
37
A large storage sac inside the cell.
Holds water, nutrients, and waste.
Helps keep the plant firm and upright by maintaining pressure.
Vacuole 💦
38
Tiny tunnels that connect plant cells to each other.
Allow water, nutrients, and signals to pass between cells, helping the plant communicate.
Plasmodesmata 🌉
39
Tiny green structures that help plants make food through photosynthesis.
They capture sunlight and turn it into energy (like a plant’s solar panel).
Chloroplasts 🌞
40
Plants Cell Parts shared with Animal Cells
Smooth ER & Rough ER: Help make and transport proteins and fats.
Golgi Apparatus: Packages and ships materials inside the cell.
Mitochondria: The "powerhouse" that makes energy for the cell.
Plasma Membrane: A thin barrier that controls what goes in and out of the cell.
41
Sclerenchyma vs. collenchyma cells
Sclerenchyma Cells:
Dead at maturity
Have thick, lignified secondary cell walls
Provide rigid structural support, especially in mature plants
Examples: Fibers (like in hemp) and Sclereids (like in pear grit)
Collenchyma Cells:
Alive at maturity
Have thickened primary cell walls (but no lignin)
Provide flexible support, especially in growing parts of the plant
Example: Found in celery stalks (those stringy bits!)
42
1) Sieve-tube elements 2) Companion cells
Phloem structure
43
Phloem Structure
1. Sieve-tube elements
2. Companion cells
44
Perforated ends Phloem
Sieve plates
45
Sieve-tube elements
long, thin cells
* Perforated ends called sieve plates
* No nuclei; directly connect to companion cells by plasmodesmata
46
Types of Growth
Primary Growth
Secondary growth
47
makes
plants taller, with longer
roots
Primary growth
48
Secondary Growth Functions
The vascular cambium helps plants grow wider (roots and shoots).
It adds more xylem (wood) and phloem, making the plant stronger and better at transporting water and nutrients.
This growth occurs in woody plants like trees.
💡 Key Idea: The vascular cambium creates wood and helps the plant get thicker and sturdier
49
Meristems
allow plants to grow throughout their lives
* Undifferentiated groups of cells that retain the ability to
undergo mitosis
50
What is responsible for primary growth
Apical meristems are at the tip of each root and shoot
51
What protects the root apical meristem?
The root cap
52
What does the root cap do?
Protects the root tip
Senses gravity for growth direction
Secretes slime to reduce friction
53
What are the three zones of a root
1. Zone of cellular division (new cells form)
2. Zone of cellular elongation (cells stretch out)
3. Zone of cellular maturation (cells specialize & root hairs grow
54
How are vascular bundles arranged in eudicots?
In a ring near the stem’s perimeter
55
How are vascular bundles arranged in monocots?
Scattered throughout the ground tissue
56
What are the two types of ground tissue in eudicots?
Pith (center)
Cortex (outer layer)
57
Secondary Growth
Cambium
Cork cambium
Vascular cambium
58
Cambium
Cells
increase the width
of the plant
* yearly secondary
growth
59
Cork cambium
the ring of cells
near the outer
perimeter
* Produces cork cells
on the outside of
the trunk
60
Vascular cambium
Produces Secondary Phloem – Helps in transporting nutrients.
Increases Stem Thickness – Allows plants to grow wider and support more branches.
Forms Annual Growth Rings – These rings in trees are used to determine age.
61
62
What is responsible for primary growth
Apical meristems are at the tip of each root and shoot
* Responsible for
63
Behind the root cap are three
populations of cells:
1. Zone of cellular division
2. Zone of cellular elongation
3. Zone of cellular maturation
64
vascular bundles arranged
They are arranged in a ring
near the stem’s perimeter
65
How is Ground tissue divided
into the central pith and the
outer cortex
66
Arrangement of monocot vascular bundles
vascular bundles are scattered through
the ground tissue
67
What is Transpiration
water moves from roots to shoots
68
When does transportation occur
1. Due to differences in water potential
2. Driven by evaporation of water from the stomata of leaves
3. Stomata are open
4. The air surrounding leaves is drier than air inside leaves
69
Potential energy
Stored energy
* The amount of potential energy an object has
depends on position or configuration.
70
What is ATP
Adenosine triphosphate
71
What does ATP do
powers nearly
all forms of cellular work
ATP is full of potential energy.
72
Kinetic energy
energy of motion (All moving objects have kinetic energy)
73
Does energy transform?
Yes Energy is often transformed from one type of
energy to the other.
74
What is Water potential
The potential energy of
water in a particular environment
75
What is net movement of water
areas of high water potential to areas of lower water potential
76
water can dissolve many substances, making it essential for life.
Water is the solvent of life
77
What is solution
a liquid consisting
of a uniform mixture of two or
more substances.
78
What is solvent
The dissolving agent (liquid)
79
What is solute
The substance that is dissolved
80
What's an aqueous solution
water is the solvent
81
What is Osmosis
movement of water through a selectively permeable barrier (Water moves from an area of low solute concentration (more water) to an area of high solute concentration (less water))
82
Examples of Osmosis
If you put a raisin in water, water moves into the raisin because the inside has a higher concentration of solutes.
If you place a freshwater fish in saltwater, water leaves its cells (causing dehydration) because saltwater has a higher solute concentration.
83
Which way will water diffuse
Water will move from a region of low solute concentration to high solute concentration
water trying to balance things out by moving where it's needed!
84
Osmosis is a special case of diffusion
When a concentration gradient exists, molecules and
ions will move from areas of high concentration to
low concentration
85
Diffusion =
spontaneous movement of molecules and
ions
86
Water potential has two components
1. Solute potential
2. Pressure potential
87
What is Solute potential
the tendency for water
to move by osmosis in response to differences
in solute concentrations
88
What is Pressure potential
the tendency of
water to move in response to pressure
89
Facts about pressure potential
In a cell, pressure potential is
wall pressure opposing turgor
pressure
90
Turgor pressure
when water
swells the plant cell, pushing
against the cell wall
91
Wall pressure
force of the
plant cell wall resisting
expansion of cell volume
92
Water potential: soil vs. root
Moist soil has high water potential, so water moves easily into plant roots.
Low water potential in soil happens when:
Soil is salty (high solute concentration).
Soil is dry, making water stick to soil particles.
When soil water potential drops, plants struggle to absorb water, leading to drought stress.
In short: Dry or salty soil makes it harder for plants to take up water! 🚫💦
93
Water potential in air
water naturally moves from the soil to the atmosphere through the plant because water flows from high to low water potential.
This water potential gradient allows water to move up a plant without energy—like water wicking up a paper towel! 🌱💧
94
Water-potential gradient
Water moves up from soil → roots → stem → leaves → atmosphere because each step has a lower water potential than the one before.
This movement happens naturally due to transpiration (water loss from leaves), which pulls water up through the plant.
💡 Key Idea: A water-potential gradient is what drives water movement in plants, keeping them hydrated! 🚰
95
Biologists have tested three major hypotheses
for how water could be transported to shoots:
1. Root pressure
2. Capillary action
3. Cohesion–tension
96
Water movement via root pressure
1. Guttation: due to root pressure can force water
droplets out of leaf margins
2. Root pressure causes guttation
97
Root Pressure & Water Movement at Night 🌿💦
Stomata close at night, reducing water loss.
Roots still absorb ions, lowering xylem water potential.
Water moves into xylem from nearby cells.
This creates positive root pressure, pushing water up the xylem.
💡 Key Idea: Even without transpiration, root pressure helps move water upward!
98
Water movement via capillary action
Is the movement of water up a narrow tube
due to three forces 1. Adhesion 2. Surface tension 3. Cohesion
99
Adhesion
creates an upward pull at the surface between water and
container
Water attracted to glass is
pulled up against the force of gravity
100
Surface tension
creates an upward pull at the top of the water column
Pulls water column up
to minimize air–water interface
101
Cohesion
Cohesion is the ability of water molecules to stick to each other due to hydrogen bonding. This property helps water move efficiently through plants.
Simple Examples of Cohesion:
Water Droplets – When water forms droplets on a surface instead of spreading out.
Water in a Straw – When you sip through a straw, water molecules stick together, helping pull more water up.
Dew Drops on Grass – In the morning, dew forms small round drops because water molecules cling to each other.
Water Moving in Plants (Cohesion-Tension Theory) – Water is pulled up from roots to leaves in a continuous stream because of cohesion.
102
Capillary action 3 parts
1. Adhesion
2. Surface tension
3. Cohesion
103
how much distance for transporting water for capillary action
root pressure and capillary action can transport
water for only a limited distance
104
Cohesion-Tension Theory
Transpiration – Water evaporates from leaves, creating tension (pulling force).
Cohesion – Water molecules stick together (like a chain) due to hydrogen bonding.
Adhesion – Water molecules stick to xylem walls, helping them move upward.
Water Potential Gradient – Water moves from high to low water potential (soil → roots → leaves → atmosphere).
💡 Key Idea: Water is pulled up the plant like a straw, using the combined forces of cohesion, adhesion, and transpiration! 🚰
105
bulk flow
The water in a column of xylem cells moves —mass movement along a pressure gradient
106
Translocation
is the movement of sugars from sources to sinks
through the phloem of a plant
* A source is a tissue where sugar enters the phloem
* A sink is a tissue where sugar exits the phloem
* Sugar concentrations are high in sources and low in sinks
107
Early in the growing season
- Storage cells in roots and
stems are sources
-Developing leaves are
sinks
108
During the growing season
* Mature leaves and stems
are sources
* Meristems, developing
leaves, flowers, seeds, and
fruits, and storage cells in
roots are sinks
109
The pressure-flow hypothesis
explains how phloem transports nutrients, primarily sugars, from source tissues (such as leaves) to sink tissues (such as roots, fruits, and growing shoots). This theory is widely accepted as the mechanism behind the movement of phloem sap in plants.
110
Differences in turgor in phloem
near source and sink
tissues generate the necessary force
Creating these differences in turgor pressure requires
energy expenditure by the plant
111
phloem loading,
Phloem loading is the process where sucrose (sugar) is actively moved from the source cells (like those in the leaves) into the companion cells and then into the sieve-tube elements (the main phloem cells).
Water follows passively: Because the sucrose makes the inside of the sieve tubes more concentrated, water moves into the sieve tubes from the nearby xylem (water-conducting tissue) to balance things out. This movement of water happens automatically (passively), without any extra energy needed.
Turgor pressure: As water enters the sieve tubes, it creates pressure in them, known as turgor pressure. This pressure helps push the phloem sap (which contains the sugar) along the plant to other areas (called sinks) where the sugar is needed.
112
phloem unloading,
cells in
the sink remove sucrose from
phloem sap by passive or
active transport
* Due to the loss of solutes, water
follows passively and turgor
pressure in the sieve-tube
elements drops
113
Phloem loading and
unloading cause
High turgor pressure near the
source
* Low turgor pressure near the
sink
* Driving phloem sap from
source to sink by bulk flow
114
There is a one-way flow of
sucrose
* And a continuous loop of
water movement
* as water flows between xylem
and sieve-tube elements
115
Macronutrients
are elements in the soil that plants
require in large quantities
116
What is an essential nutrient for plants?
An element or compound required for normal growth and reproduction.
117
How many essential elements do most vascular plants need?
17 essential elements.
118
What three elements make up 96% of a plant’s dry mass?
Carbon (C), Hydrogen (H), and Oxygen (O).
119
What are macronutrients, and why are they important?
Elements plants need in large amounts; they are important for growth and metabolism
120
Name three limiting macronutrients that affect plant growth.
Nitrogen (N), Phosphorus (P), and Potassium (K).
121
What are micronutrients, and what is their role?
Elements required in small amounts, usually acting as enzyme cofactors.
122
Give four examples of micronutrients.
Iron (Fe), Zinc (Zn), Boron (B), and Copper (Cu).
123
What happens when mobile nutrients are in short supply?
They move from older leaves to newer leaves, causing older leaves to deteriorate
124
Give three examples of mobile nutrients.
Nitrogen (N), Phosphorus (P), and Potassium (K).
125
What happens when immobile nutrients are in short supply?
They stay in older leaves, so newer leaves show deficiency symptoms.
126
Give three examples of immobile nutrients.
Calcium (Ca), Iron (Fe), and Copper (Cu)
127
In what form do elements required for plant growth occur in soil?
As ions (either anions or cations).
128
What are anions, and how do they behave in soil?
Negatively charged ions that dissolve in soil water and are easily washed away by rain.
129
What is leaching?
The loss of nutrients from soil due to water movement.
130
hat are cations, and how do they behave in soil?
Positively charged ions that dissolve in soil water but stick to negatively charged particles, making them less immediately available.
131
Name two things that cations interact with in soil.
Negatively charged organic matter and mineral anions on clay surfaces.
132
Why can’t plants use atmospheric nitrogen (N₂) directly?
Because plants cannot break down nitrogen gas on their own.
133
What is nitrogen fixation?
The process where bacteria and archaea convert N₂ from the atmosphere into ammonia (NH₃), nitrites (NO₂), and nitrates (NO₃)
134
In what forms do plants absorb nitrogen?
As ammonium (NH₄⁺) and nitrate (NO₃⁻) ions.
135
What organisms help plants with nitrogen fixation?
The process where bacteria and archaea convert N₂ from the atmosphere into ammonia (NH₃), nitrites (NO₂), and nitrates (NO₃).
136
In what forms do plants absorb nitrogen?
As ammonium (NH₄⁺) and nitrate (NO₃⁻) ions.
137
What organisms help plants with nitrogen fixation?
Certain bacteria and archaea that live in soil or in nodules on plant roots.
138
What are root nodules?
Structures on plant roots that house nitrogen-fixing bacteria.
139
What percentage of plants are autotrophs?
99% of living plants are autotrophs
140
How do parasitic plants obtain nutrients?
They extract water and nutrients from a host plant’s xylem, reducing the host’s fitness.
141
What is a heterotrophic parasitic plant?
A plant that completely relies on its host for both water and nutrients.
142
What are epiphytes, and how do they get nutrients?
They are plants that grow without soil, absorbing nutrients from rainwater, dust, and particles in the air.
143
How do carnivorous plants obtain nutrients?
They trap and digest insects to absorb nitrogen and other nutrients.
144
Where are carnivorous plants usually found?
In bogs or nutrient-poor soils where nitrogen is scarce.
145
