Bio part 4

What are plants, how are they like animals and what do they need to do to survive and what do these processes need

• Plants are multicellular organisms with many of the same requirements as animals.

• They need to reproduce, repair their tissues, grow, and excrete waste- all of these require energy.

How do plants produce energy?

Energy is produced through the process of cellular respiration:

• Food (Glucose) + Oxygen → Carbon Dioxide + Water + Energy

• Cellular respiration breaks down glucose into cellular energy (ATP-what the plants actually use)

• Another way to write the above equation (js more scientifically) is: C₆H₁₂O₆ + 6O₂ → 6 CO₂ + 6 H₂O + ATP (adenosine triphosphate)- ATP is the actual thing they use

The glucose is produced by photosynthesis since plants are autotrophs:

• 6 CO₂ + 6 H₂O + light + chlorophyll → C₆H₁₂O₆ + 6 O₂

Note: Photosynthesis uses products of cellular respiration to produce reactants of cellular respiration

• Plants need to use the energy they make thru photosynthesis in order to survive

These two processes are complimentary- one depends on the other.

What structures do plants have that allow them to get energy? What is the purpose of the underground structures of plants?

• There must be tissues which transport the nutrients and gases from the environment to the plant’s cells. These tissues are different from those found in animals.

• Plants do not have organ systems as found in animals. Instead, they have two main body systems; the root system and the shoot system.

• Below ground structures r js for absorption

Label and add a note abt herbaceous vs woody stems and leaves

Notes: Herbaceous stems= green and can photosynthesize, woody stems-have things like bark that don’t photosynthesize, leaves do photosynthesize

Root system (plants)- include what structures it has + what the purpose of these structures is, what an exception is and why these exceptions developed, add examples

This system consists of all the below ground structures** that:

• Anchor the plant- hold it in place

• Absorb water and minerals from the ground 

• Store food for later use 

**  Some plants have roots above the ground.  These are special adaptations to their environment.

• Eg. mangroves, banyan trees, orchids

Know diagram

Shoot system of plants- include what structures it consists of + what the function of these structures is, and what the parts of the shoot system are

This system consists of all of the above ground structures that are specialized for two main functions:

• Conduct photosynthesis or contribute substances to the process 

• Reproduction- eg. mosses that produce sporangium, flowers with pollen and stuff, etc.

There are three parts to the shoot system:

1. Flowers

2. Leaves

3. Stems

Flowers (part of shoot system)- include what they are developed for, what they are, what each part of the flower does and how this is important, what some plants have, what a hermaphroditic plant is, what a monoecious plant is + example, what a dioecious plant is + example, and identify what type of flower plant each plant in the diagram is

• These are specialized structures developed for sexual reproduction.

• The male reproductive structures produce the pollen grains and have modifications to ensure the pollen is distributed.

• The female reproductive structures accept the pollen and ensure it fertilizes the egg to form the seed which is contained within the fruit.

• Some plants contain both male and female structures. 

• If both sex structures are in the same flower it is called a hermaphroditic plant 

• If there are separate male and female flowers but they are on the same plant it is a monoecious (one plant) plant such as corn, cucumber, and begonia.

• Other species have separate male and female plants.  These are called dioecious (2 plants) plants such as holly, kiwi, and asparagus.

Know the diagram- be able to identify which is which

Leaves (part of shoot system)- include what they function to do, and what they can provide to the plant + examples

 These are the primary sites for photosynthesis.

      They can also provide:

• Support such as tendrils on grape vine 

• Protection such as thorns, spikes- eg. cacti 

• Attraction of pollinators- eg. red leaves on poinsettia (the red is not the flower js the leaves used to attract pollen)

Stems (part of shoot system)- include their functions

The stem has several functions:

• Support for the branches, leaves, and flowers 

• Movement of water from the roots upward to all plant parts

• Transportation of food up and down to where it is to be used or stored

• Storage of excess food 

• Protection 

• Photosynthesis 

SMTSPP

M SPPTS

What is a monocotyledon (monocot) vs dicotyledon (dicot)- also include why the difference between the 2 is important and where these differences are seen in plants

Monocot:

• Contain species with long, thin leaves such as grasses, orchids, and lilies.

• Only have one cotyledon

Dicot:

• Larger group of Angiosperms and have broad-leaf species like dandelions, canola, and maple trees.

• Have 2 cotyledons

This important difference results in very distinct noticeable features that allows us to identify if a plant is a monocot or a dicot.

These differences are found in all of the plant parts.

Contrast between monocot root systems and dicot root systems. Provide examples of each.

Monocot roots:

• Have fibrous root systems (a mat of thin roots spread out below the soil’s surface + provide an increased exposure to the soil’s nutrients and water

• Examples: Grass, onions and lilies

Dicot roots:

• Have a taproot root system- has one large vertical root with many smaller branches)

• Examples: Carrots, roots and beets

Provide 2 examples of a root modification that allows the plant to be better adapted to its environment.

• Buttress roots  form on some tall or shallowly rooted tree species to help support them

• Mangrove trees have above-ground roots that help bring oxygen into the roots

What is the definition of a shoot?

Above-ground structures of a plant that have stems, leaves and flowers.

Compare nodes and internodes of a stem.

Nodes:

• Points on the stem where leaves are attached

Internodes:

• Portions of the stem between nodes

What is a bud? What is the difference between a terminal bud and an axillary bud?

Undeveloped shoots.

Terminal bud= found at the tip of a stem

Axillary bud= found in the angles formed by a leaf and the main stem (angles are called axils). Growth from the axillary bud forms the plant’s branches

What is a leaf?

• The primary food-manufacturing sites of a plant

• Capture sunlight and convert light energy to chemical energy thru photosynthesis

• Most plant leaves are flattened and thin to allow them to intercept and capture sunlight effectively

Label

Note the differences between the venation of the leaves of a monocot vs a dicot

• Dicots are more like ur typical leaf with striked venation while monocots have parallel venation

• Lily= monocot, Daisy= dicot

How are leaves protected from losing too much water?

They have coated waxy cuticles

What are some ways plants protect themselves from herbivores?

Cactus leaves have spikes so that they’re pointy and don’t look like leaves- herbivores won’t eat.

What is a flower?

• Plays an important role in reproduction of plants

• A specialized shoot, unique to angiosperm, that usually consists of four different rings of modified leaves: sepals, petals, stamens and pistils

Label the diagrams of this hermaphroditic plant

Sepal- describe function

Covers and protects the flower bud before the blossom opens

Petal- describe function

Usually colorful, soma have “runaway” markings that help guide insect pollinators toward the flower’s reproductive parts

Stamen- describe function

Closer to the center of the flower, the male reproductive structures of the flower, male gametophytes are produced here

Pistil- describe function

At the center of the flower, the female reproductive structures of the flower

Anther- describe function

Within these structures, meiosis produces spores that develop into pollen grains (each pollen grain is a male gametophyte)

Filament- describe function

Holds the anther up

Stigma- describe function

The sticky tip of a style, pollen grains released from the anthers of the flower land here (stigmata=plural)

Style- describe function

The narrow structure leading to the ovary

Ovary- describe function

The structure at the base of each female pistil, contains the ovules

Ovule- describe function

Contain female gametophytes that when fertilized develop into seeds

Complete the table contrasting monocot flowers and dicot flowers- include the features (Petals, sepals, and reproductive parts in multiples of …. and Petal arrangement/grouping differences)

Feature	Monocot	Dicot
Petals, sepals, and reproductive parts in multiples of ….	Tend to have these structures in multiples of 3 (3, 6, 9, etc.)	Tend to have these structures in multiples of 4 or 5 (4, 8, etc. or 5, 10, etc.)
Petal arrangement/grouping	Undifferentiated petals and sepals	Have distinct separate petals and sepals

What is an inflorescence? Provide examples of plants with an inflorescence

A cluster of flowers arranged on the plant stem. Describes how flowers are arranged. Example= sunflower (because it appears to be a single flower but is actually a cluster of individual flowers called florets).

What happens during pollination?

• During pollination, pollen grains released from anthers land on the stigmata of the flowers. Typically, this is after the pollen has been carried by wind or an animal to another flower.

• Once on a stigmata, a pollen grain absorbs water and extends a structure called a pollen tube. The pollen tube, which contains 2 sperm nuclei, grows toward the ovary through the style.

• When the pollen tube reaches the ovule in the ovary, a sperm cell fertilizes the egg cell in the ovule and forms a zygote, which develops into the plant embryo.

• The other sperm cell contributes to the development of a nutrient rich tissue called endosperm that nourishes the growing embryo.

• Several pollen tubes may grow down a style at once, competing with one another to fertilize one ovule.

What exactly are the “silks” on ears of corn?

They’re the styles and stigmata of the female flower that catch the pollen blowing in the wind.

Provide 3 methods plants use to attract pollinators.

• Specific scents- sweet, fresh, strong, etc.

• Bright colours- eg. blue, yellow, red

• Containing nectar or pollen- attracts insects like butterflies or bees that use these things for food

Monocot (Corn)- label

Label dicot (bean)

Define Seed Coat + function

Tough outer layer of the seed, helps protect the tiny embryo and endosperm inside the seeds.

Define Endosperm + function

A nutrient-rich tissue that nourishes the growing embryo

Define Cotyledon + function

An embryonic leaf, helps with the storage and transfer of nutrient to the embryo + very important in seeds without endosperms

Explain how a plant’s production of a fruit can aid in seed dispersal.

A fruit develops in the ovary of the angiosperm, fruits function to protect seeds and help disperse seeds from the parent plant. This helps with seed dispersal because seeds can travel by sticking onto a passing animal’s fur as burrs (burrs are a fruit), some seeds are tucked inside edible fruits that are attractive to animals as food- the seeds coat is indigestible therefore it goes through the animal’s digestive tract and is deposited as the animal’s feces, etc.

Provide other examples of seed dispersal methods.

Some seeds are so tiny and lightweight that they can be carried by wind (e.g. dandelion seeds), some are ballistically propelled from the plant, etc.

What is dormancy?

Slow or completely stopped growth of the plant in response to drought, cold or low light levels.

What is germination? What happens in order for germination to occur? Why is this necessary?

When conditions are favourable, the plant embryo within a seed begins to grow (called germination). Most seeds must soak up water in order to germinate- allows the seed to expand and split its seed coat. The water also triggers metabolic changes in the embryo that enables it to grow.

Provide examples of special conditions needed by some plants in order for germination to occur.

Some desert plants germinate only after a heavy rainfall (other plants usually just require moist environments)- because it allows the seedling to push more easily though the moistened soil and ensures a temporary water supply that can be used by its growing tissues, in climates with harsh winters, some seed will germinate only after being exposed to a long period of cold- prevents them from germinating during a warm spell in the middle of the winter , some require exposure to intense heat of a brush fire- the fire clears dense shrubs and other growth that would otherwise shade and compete with the seedling, etc.

Describe the differences in germination between monocots (corn as an example) and dicots (beans as an example).

Monocot (corn):

• A sheath surrounding the shoot pushes straight upward, breaking through the soil. The delicate shoot then grows upward through this protective tunnel. After emerging into the light, the first leaves expand from the shoot and begin making food by photosynthesis. At this stage, the young plant is called a seedling.

Dicot (bean):

• Some dicots have a hooked shoot type- this protects the delicate shoot tip by holding it downward as the shoot moves through the soil. As the shoot breaks through the soil surface, its tip is lifted gently out of the soil and straightens out.

Know the stages in the diagram

How does the seed of a flower grow after being fertilized by a pollen grain? What do the cells of the plant do as the seed develops in the embryo and what must the plant be able to do

• Once the ovule has been fertilized by the pollen grain the seed begins to grow by the process of mitosis.

• As the seed develops into the embryo, the cells begin to differentiate into the specific tissues that plants require.

• Plants must also be able to respond to their environment and modify their growth and differentiation.

Types of Plant Growth- if all cells of a plant differentiate and if not what they do instead and what these can become. Also include the types of this growth

Not all of the cells differentiate. Special areas contain unspecialized cells called meristematic cells (stem cells) which are able to become any type of specialized cell. These cells are needed so the plant can grow. Types of growth with meristematic cells are:

1. Primary Growth - Apical Meristems (taller/longer)

2. Secondary Growth - Lateral Meristems (only in woody dicots) (wider)

Primary Growth - Apical Meristems (taller/longer)- include where the meristematic regions are and what they are needed for + where the growth occurs

The meristematic regions are located at the tips of the plant’s roots and shoots. These regions are needed to increase the length of the tissues. Contains growth at the:

1. Root Tip

2. Stem tip

Root tip (Primary plant growth)

When the meristem cells first divide, many of them begin to elongate which makes the root longer.  As they elongate they begin to differentiate into the specialized cells of the dermal, ground, and vascular tissues systems.  Once their job is set they cannot continue to grow or divide.

Note: These do have apical meristems (a region of actively dividing, undifferentiated cells found at the tips of plant roots and shoots).

ask miss barrick if we need to know these pics

Stem tip (primary plant growth)

Growth in the apical meristems is more complex. They are located in the buds at the very tips of the growing system. These areas also allow plants to grow side branches off the main stem. Cells produced by the apical meristems divide and specialize as they form the new tissue systems of the stems, leaves and flowers.

ask miss barrick if we need to know these pics

Secondary Growth - Lateral Meristems (only in woody dicots) (wider)- include where they are located in what parts of plants and what this region is called + what it enables, what the inner meristem is (what its referred to, what it does, what some cells here do, and what the thing they become is called), what happens with each cell division in the vascular cambium (what is produced), what the outer meristem is (where it is, what it helps with and how it does this), what will happen if a cork of a tree is removed and why, and what happens with the vascular cambium every year

There are meristematic cells located just beneath the outside layer of the stem of woody plants.  These regions are called lateral meristems which enable the plant to grow wider.  

The inner meristem is referred to as the vascular cambium (basically connecting all the phloem and xylem together → make the rings of a tree).  The cells along the outside of the vascular cambium produce secondary phloem. The cells along the inside of the vascular cambium become the secondary xylem and as they enlarge they push the rest of the cells outward. The secondary xylem is called the wood.

Each cell division in the vascular cambium produces one new xylem cell and one new phloem cell.

The outer meristem (on the outside, basically the bark of a tree) helps the plant grow wider by replacing the epidermis with new dermal tissue, called cork. These new cells form the bark of the plant.

• A tree will die if all it’s cork is removed (because it can’t get sugars to the roots), except for cork trees (how we get cork) because they can regrow their cork

Every year, the vascular cambium produces new secondary xylem and phloem.  The secondary vascular tissue eventually crushes the primary phloem (basically replaces it).

ask if we need to know diagram

Plant Growth Regulators- what are they, how do they occur (in general), and name the regulator groups

Plants can modify their development in response to the environment. The responses are regulated through the production of plant hormones called plant growth regulators. These chemicals act by signaling the plant cells to undergo changes.

1. Auxins

2. Cytokines

3. Gibberellins

4. Abscisic Acid (ABA)

5. Ethene (Ethylene)

Auxins (plant growth regulator group)

• These are a group of compounds that promote cell elongation and the primary site for their production is the shoot apical meristem.

• They also stimulate cell division in the vascular cambium and promote the formation of new lateral meristems and new root apical meristems.

Cytokines (plant growth regulator group)

• These chemicals promote cell division. They are found in tissues that are actively dividing, such as meristems, young leaves, and growing leaves.

• They also slow cell aging in certain plant organs.

Gibberellins (plant growth regulator group)

• Occur later in the plant’s growth when it’s getting ready to flower

• This group of more than 100 different compounds promotes cell division and cell elongation. They have a strong effect on the size of the plant.

• They also have a role in flowering and fruit production in many species.

Abscisic Acid (ABA) (plant growth regulator group)

• ABA stops cell division in the buds and in the vascular cambium therefore no primary and secondary growth.

• It is important when the plant needs to stop its growth and reproduction such as when the temperature gets cold in the fall and the plant goes dormant. The levels of ABA rise in response to lower temperatures and less light.

• It also controls the closing of stomata when it is dry. Wilting causes the mesophyll cells in the leaf to produce ABA which causes the mesophyll cells in the leaf to produce ABA which causes the guard cells to close, conserving water.

Ethene (Ethylene) (plant growth regulator group)

• Ethene is a gas that stimulates many developmental stages. These include fruit ripening, shoot and root growth, flower opening, leaf and fruit drop, and leaf and flower maturation.

• All of the plant hormones work together and may be influenced by each other. The action of the plant hormones is quite complex.

Plant Response to the Environment- include what a tropism is + what these responses are controlled by and the types of tropism

A tropism is a change in the direction of growth or movement of a plant in response to a stimulus. These responses are controlled by the plant growth regulators.

1. Phototropism

2. Gravitropism

3. Thigmotropism

Phototropism- include what it is, who it was first studied by + how they studied it and what they hypothesized based on what they observed, what it was found that this person had discovered, and what the discovery was

• This is a change in the direction of growth of a plant in response to light. The plant is detecting and responding to uneven lighting in its environment.

• This effect was first studied by Charles Darwin. He removed the shoot tip of some plants. When placed in a sunny window, the plants with no shoot tip kept growth straight upward while those with the shoot tip bent toward the window.

• Darwin hypothesized that a shoot tip detects light and transmits a signal down to the growing region of the shoot.

• Darwin in fact had discovered the first plant hormone, auxin.

• When a plant is exposed to light from one direction, auxin builds up on the shaded side and stimulates cell growth. Cells on the shaded side elongate more than cells on the lighted side and the shoot bends toward the light source.

Gravitropism- include what it is, what is important in this tropism, and what it helps with in a plant

This is a change in the direction of growth in response to gravity.  

The root cap is important in helping the root grow down.

• Basically just so that the roots always know how to grow down

Thigmotropism- include what it is, what is important for this process and an example

• This is the change in the direction of growth in response to contact.

• Ethene is important in thigmotropism of roots and shoots. For example, if a root touches a stone, the root cells are stimulated to produce ethane which causes the root to grow sideways. When the root no longer touches the stone, ethane is no longer produced and the root grows downward again.

Name and describe the structure that protects the tip of a growing root

Root cap -> cone of cells that covers the delicate, actively growing cells of the apical meristem

Describe how elongation occurs during the primary growth of roots and shoots

Primary growth of roots and shoots depends not only on the addition of new cells by the apical meristem, but on those new cells getting longer as they take up water. This process of elongation forces the root tip through the soil. In a shoot, elongation occurs just below the terminal bud. The elongating cells push the apical meristem upward in the stem and downward in the root.

Describe the 2 roles of the root’s apical meristem in primary growth

The roots apical meristem replaces the cells of the root cap that are scraped away by the soil and produces the cells for primary growth

Identify and describe the 2 types of tissue generated by the vascular cambium that contribute to secondary growth

The vascular cambium produces secondary xylem (or wood) toward the inside of the stem and secondary phloem toward the outside of the stem

Distinguish between the location and function of apical meristems, vascular cambium and cork cambium

Apical meristem -> root and shoot tip -> primary growth of root and shoot

Vascular cambium-> Between xylem and phloem in shoot and root -> produces secondary xylem and phloem, increasing girth of stem and root

Cork cambium -> outside secondary phloem in woody stem -> produces outer layer of protective cork

Examine the photo of a root cross section and identify tissues A-C

a) Epidermis

b) Cortex

c) Xylem

Explain why each of the following statements is incomplete or incorrect:

a) Tree trunks are made of dead cells

b) Once cork cambium is shed with the rest of the bark, new cork cannot be formed

a) Statement is incomplete. Dead cells are present but also many living cells. The bulk of the tree trunk is made of wood formed by xylem vessel elements that are dead at maturity.

b) Incorrect. The cork cambium produces a steady supply of new cork, keeping pace with growth from the vascular cambium. Cork cambium is shed with the rest of the bark, new cork cambium continuously generates from parenchyma cells in the still-living phloem.

Examine the cross section of a tree trunk below.

a) Approximately how old was this tree when it was cut down?

b) Match the letters on the photograph with the descriptions below, and explain each choice

i) In this year, there was probably a drought

ii) In this year, spring was long and wet, and summer was short and hot

a) 15 year old

b)

i) B -> produces narrow, thick-walled xylem cells (very narrow due to little growth because of drought)

ii) A -> Produced large and thin-walled xylem that could carry lots of water

How do Earth Stars (plant) travel/spread?

When raindrops hit them (they open at a time of year with lots of rain), they gain enough energy to propel their spores into the air

How do Dandelion (plant) travel/spread?

• They use the wind to propel their seeds to new places

• After their petals fall, they form globes with 100 or so seeds that spread out when the wind blows

• The seeds have their own parachute like structures that allow them to move with the wind because their heftier than fungi spores

How do Cottonwood Tree (plant) travel/spread?

They provide their seeds with straightforward fluff

• Because of the tree’s high, the seeds are able to travel miles in the wind

• They will land in the water and can end up on the shores of Germany

How do Liana Tree (plant) travel/spread?

• Less wind so its seeds have wing-like structures that allow even small winds to cause the seeds to be able to glide on the wind and spread out

How do Squirting Cucumber (plant) travel/spread?

They use explosives or jet propulsion 

• The plant explodes spreading the seeds

• Uses liquid to propel the seeds

• Kind of similar to a plant spitting it’s seeds out

How do Himalayan Balsam (plant) travel/spread?

• It’s seed capsules are are filled with liquid to the point where the pressure is so high that they explode with the lightest touch- can shoot their seeds as far as 15 ft away

How do Burdock (plant) travel/spread?

• Uses hundreds of hooks to latch onto animals with fur (like dogs) to spread their seed sout

• Uses burrs (the thing that actually has the seeds and hooks in it)

How do Durian Plant (plant) travel/spread?

• Has a very strong smell that it uses to attract animals (eg. orangutans)- animals can then carry the seeds of the fruit and distribute it as waste somewhere else

How do “Rhino apple” (plant) travel/spread?

• Rhinos eat the fruits and then move them to areas where they may be less shade so that the plant can reproduce (because rhinos eat in the forest but later in the day move to open grasslands)

• Excrete the seeds of the fruit they ate

How do Acacia plant (plant) travel/spread?

• Elephants eat the acacia trees plant (specifically the tree pods) without grinding the fruit up too much like monkeys- allows the seeds to survive and be excreted somewhere else

• The elephant get rid of the remains (excretes) with the seeds within while also getting rid of insects that feed on the seeds through digestion

How do Brazil nut (plant) travel/spread?

• Like a cannonball (fall of a couple hundred feet doesn’t crack them)

• Seeds are contained in hard capsules- the capsules can only be opened by the agouti (animal)- have 2 sharp front teeth

• The agouti eats the seeds in the capsule, except the capsules have 15-20 nuts in each capsule (more than one agouti will eat at once)

• Because of this, the agouti will bury these nuts to eat later, but will often forget where all the nuts are buried allowing the seeds to grow

How do Arolla (plant) travel/spread?

• Alpine nutcracker (bird)- opens the cones of the arolla and picks out the ripe seeds

• The bird will swallow the seed but not fully eat all of them- hides the for later but regularly takes the seeds away from the forest and onto open ground/ high alpine meadows (cause it can memorize landmarks easier to find the seeds better later)- allows the arolla pine to grow in a good environment (hidden from predators and at a good depth)

How do Protea (plant) travel/spread?

• Can have their seeds ready and waiting for years without being released

• Seeds are inside seed pods

• Depend on seasonal fires to spread out their seeds- because their seed heads have to be burnt before they can release their seeds

• Also, fire kill adult plants which makes a perfect time for seeds to germinate as there are no competitors

• Once they are burned though (abt an hour later), the heads open, and the ash acts as a nutritious bed for the seeds

• When right conditions arrive, the seeds will start to grow (can remain alive without growing for a long time)

How do Magnolia (plant) travel/spread?

• Can survive a very long time before releasing flower buds

What are the 4 main factors that can affect a plant’s growth?

Soil, water, salt, and temperature can affect a plant’s growth.

Besides growth, how else can the above factors impact the plant?

These factors (soil, water, salt, etc.) also help with reproduction and survival or a plant.

How do many plants withstand temporary stress?

Plants tend to go dormant to withstand temporary stress.

Describe how the Purple saxifrage is adapted to Canada’s harsh arctic environment.

The plant forms low dense mats that protect it from the drying wind in the arctic.

Drought is a prolonged period of inadequate rainfall.

a) What effect does drought have on plants?

b) How do plants respond to drought conditions?

a)

• It can stress or weaken plants (especially if the plants are not adapted to survive long periods without enough water). 

• Plants can lose most of their water through transpiration (absorbing water through roots and releasing it as vapour) than they get from the soil- causes a shortage of water and inhibits plant growth  (specifically in the leaves which can reduce photosynthesis)

b)

• They conserve their water- close their stomata to slow down the rate of transpiration

Provide examples of adaptations that have developed to allow plants to withstand drought conditions

• Plants like cacti and succulents store water in their fleshy stems

• Cacti also have spines that are their modified version of leaves (because normal flat leaves would lose a lot of water during transpiration)

• The green, fleshy stems become the main organs used in photosynthesis instead- for cacti

• Succulents (like jade plants and Aloe vera) adapted to have thick fleshy leaves (rather than thin ones) with thick cuticles (both in their leaves and stems)

What effects does flooding have on the plant’s environment?

• Soil that is waterlogged (too much water basically) doesn’t have enough air spaces to provide oxygen for cellular respiration in the plant’s roots

• Oxygen also moves more slowly in water than in air- makes it harder for plants to get oxygen basically

Provide an example of a plant that is adapted to very wet habitats.

Mangrove trees:

• Grow in coastal marshes

• Rots are partly above ground- allow the plant to get oxygen for the underwater part of the roots

What are the problems with waterlogged soils?

• Causes a lack of oxygen- normally soil has air packets but when there’s too much water in the soil there are less of these air packets- causes roots of the plants to suffocate and die

What is a problem with excess salt in the soil?

• Root cells lose water to the soil through osmosis (water moves from high concen places to low concen places)

Provide some examples of how plants have adapted to salty environments.

• Halophytes (type of plant) can remove salt from the plant (are salt-tolerant)

• Some species of halophytes have salt glands that pump salt out of the plant across the leaf epidermis, allowing rain to wash the salt away- basically get rid of the excess salt themselves

• Pickleweed plant can pump excess salt to stems a the tips of the plant- then it will shed these stems to get rid of the salt

What is a plant’s first line of defense against infection?

The physical barrier of the plant's epidermis and the waxy cuticle that covers it

What is the second line of defense?

• Chemicals- some are antimicrobial

• E.g. some chemical defenses attack molecules in the cell wall of a bacterium while other chemicals can signal lignin production (hardens the cell walls around the infected area and seals off the invading pathogen from the rest of the plant- prevents spread)

What are some plant defenses against animals feeding on them?

• Plants may have physical defenses like thorns or chemical defenses like poison

• E.g. when exposed to light, potato tubers produce a bitter chemical called solanine which is fungicide and insecticide (acts as a nature defense that protects the tubers fro benign eaten)- therefore chlorophyll in potatoes means the potatoes have been exposed to light which can be signal that the tuber contains solanine