Biology Exam- 2024

Vascular Plants

Vascular Plants

plants that have a system which allows them to transport materials throughout the plant.

Two main types are: Gymnosperms & Angiosperms

Gymnosperms

• seeds are produced in cones without fruit around them

• have needles for leaves

• do not produce flowers but have vascular tissues

• thrive in long, cold winters and low nutrient levels in the soil.

Angiosperms

• plants that produce flowers

• important food source for animals including humans

can be grouped into two Classes

1. Monocotyledons (monocots)

2. dicotyledons (dicots)

monocots

seed leaves: one cotyledon

veins in leaves: usually parallel

vascular bundles in stems: scattered

flower parts: multiples of three

dicots

seed leaves: two cotyledon

veins in leaves: usually netlike

vascular bundles in stems: arranged in ring

flower parts: multiples of four or five

Cotyledon

first “leaf developed by the embryo of a seed in a plant

Vascular Tissues in Plants

There are two main types of vascular tissue:

1. Xylem

2. Pholem

These tissues are responsible for transporting needed materials throughout the plant

Xylem and Phloem are located in structures called vascular bundles. Vascular bundles are arranged differently in monocots compared to dicots

Xylem

Structure:

• Hollow, thick-walled with open tapered ends

• Form lon tubes when joined end to end from the root tips to shoot tips

• dead when mature

Function:

• Deliver water and dissolved minerals throughout the plant

• Provide strength for stems and roots

• Two kinds of xylem: vessel cells and tracheid cells

Phloem

Structure:

• Thick walls with sieve-like ends

• Alive when mature but do not have a nucleus

• Form long tubes from roots to shoot tips

Function:

• Deliver dissolved sugars and nutrients throughout the plant

• Provide strength for stems and roots

Companion Cells Function:

• Control the activity of the sieve tube cells

Transport in Xylem

Xylem transports water and dissolved minerals

1. Root Presuure

• Roots can build up pressure that forces water upward.

2. Capillary Action

• water is attracted to the insides of xylem cell walls (long tubular structures)

• Water will cling to the tube and "climb" upwards a little due to adhesion.

3. Transpiration-Tension Theory (Cohesion-Tension)

• water molecules in the xylem are pulled up.

• Molecules of water in the xylem tubes are attracted to one another by hydrogen bonds. This is called cohesion.

Transport in Phloem

• Sieve tubes must be alive to function.

• Materials move up and down in the same tubes at different times

• Transport can occur very rapidly (5500 g in less than one month in pumpkins.)

• Lack of oxygen and low temperatures slow the transport but do not stop it completely.

Function of Roots

• absorb water and dissolved minerals for plant and transport to the rest of the plant

• anchor plant

• storage of nutrients

Taproot

grows a long, thick, tapered root from which a few smaller secondary roots grow, (Ex: Carrot, beetroots, radishes)

Advantages:

• Grows deep into soil to obtain moisture

• Stores lots of nutrients in the root

Fibrous Root

grows a mass of mine roots which spread out over a wide area. Ex: grass

Advantages

• Spreads over a wide area to obtain moisture and nutrients

Modified Roots

Some roots are modified to provide extra support for a plant or to store food and water.

Ex: sweet potatoes are modified to store food and water

Root Tissues

Epidermis: single layer of cells surrounds the root, stem and leaves and acts as a protective layer

Root hairs: extensions of epidermis cells which dramatically increase surface area available for water absorption

Cortex: made of large parenchyma cells which contain large vacuoles for food storage (usually starch)

​​Endodermis: layer of cells surrounding the vascular tissue in the root (allowing only water and needed dissolved minerals in)

Vascular cylinder: xylem & phloem surrounded by the endodermis

Stems

• may be herbaceous (soft, green, fleshy) or woody (stiff with wood tissues).

• begin as herbaceous stems.

• Some develop wood tissues through growing season and become perennial, while others die and do not survive the winter (annual).

parts of a stem

• Cortex: irregular cells in shape and arrangement which are general storage cells (also found in roots)

• Pith: similar to cortex cells, but usually spongier because the cell walls are thinner and there are more air spaces between them

Pith cells are in the very centre region of a stem, while cortex cells surround them and vascular bundles in young stems.

Stem Adaptations

1. Rhizomes

• horizontal underground stems that grow thin roots.

• new plants can emerge from the rhizome grasses (ex: irises )

2. Stolons

• horizontal above-ground stems.

• At nodes, roots can emerge and a new plant can be formed.

• (ex: Strawberry plants grow stolons and become strawberry patches.)

3. Tubers

• Thickened areas at the end of rhizomes, are usually used for food storage. (Ex: potatoes)

• Potato tubers on the roots of a potato plant

4. Corms

• Thickened stems which remain underground. Resemble bulbs in shape

• (bulbs are underground leaves not stems)

Leaf Tissues

• Cuticle: a waxy layer on the surfaces of the leaf which prevents excess water loss

• Epidermis: small, colourless cells on the surfaces of the leaves which manufacture cuticle and are a protective layer

• Mesophyll: cells specialized for photosynthesis

  • Two types: palisade- arranged in tight tow

    sponge- air spaces between

• Vein: contains the vascular tissue (xylem and phloem)

  • (a vascular bundle in a lead is a vein)

Guard Cells

• pair of guard cells are attached together at both ends.

• when water enters the guard cells, forces the cells to buckle outwards creating the stoma opening.

• When water leaves the guard cells, they become flaccid and the stoma close. (this occurs when it gets too dark for photosynthesis or when there is not enough water)

In general, stomata are open in the day and closed at night, also close during very dry, hot conditions

reproduction in plants

• flower is the reproductive structure of plants.

• flowers have both male and female reproductive structures.

• male gametes (sex cells) are located in the pollen grains

• egg cells are located in the ovary of the flower.

Fertilization (pollination) of plants occurs when the pollen grains reach the egg cells.

stamen

• When pollination happens, pollen is produced by the male part of the flower, called the stamen.

• The end of the stamen is called the anther, and that's where pollen is made.

• Pollen contains the genetic information.

Sexual Reproduction in plants

Fertilization is when this pollen travels down the pistil of the flower and reaches the egg cells in the ovary (which also contain genetic information).

• When the DNA combines, seeds are produced.

• Flowers can cross-pollinate or self-pollinate.

Asexual Reproduction

• only one parent is needed, and the copies that are made are genetically identical.

• Plant cuttings can be used to propagate plants, and is called vegetative propagation.

In grafting, one plant can be combined with another.

• a part of a plant is attached to another plant (with its own root system).

• A new plant grows as a combination of the two - the introduced plant part can now use the root system of the other plant.

Reproductive System of an Angiosperm

A. Anther: pollen is stored and produced

B. Pollen Grains: cases containing male gametes

C. Stigma: sticky “lip: of pistil that collects pollen grains

D. Style: stalk that supports stigma

E. Ovary: swollen base of pistils, contains ovules

F. Ovules: sacs containing female gametes

filament: stalk that supports anther

Tropism

growth of a plant toward or away from a stimulus

Thigmotropism

growth of a plant toward or away from touch (ex: grape tendrils grow around wires

Geotropism (gravitropism)

Growth of a plant in response to gravitational pull (eg: roots grow toward gravitational pull but stems grow away)

Hydrotropism

Growth of a plant in response to moisture (eg: roots grow toward source of moisture in the soil)

phototropism

Growth of a plant in response to light (eg: growth of plant leaves and stems to angle toward the light)

Nastic Movements

• plant responses to stimuli hat are independent of direction.

• response is quick and reversible, but not growth-related

eg: the venus fly trap quickly closes its leaves to capture an insect, mimosa leaves immediately droop when touched

Plant Hormones (Growth Regulators)

Auxins:

• promote elongation of cells

• stimulate root growth & ripening of fruit

Gibberellins:

• promote cell division and elongation

• cause enlargement of fruits

Cytokinins:

• stimulate cell division and leaf growth

• cut flowers sprayed with cytokinins extend their shelf life

Abscisic Acid:

• inhibits growth

• causes dormancy of seeds

• causes the closing of stomata

Ethylene:

• gas which stimulates fruit ripening

• involved with colour changes and softening of fruit as it ripens

Crop Rotation

different crops are planted each year or fields are left to lie fallow (rest)

Circulatory System Organs & Function

Heart

To distribute blood and other nutrients to all your body’s organs and tissues.

Digestive System Organs & Function

esophagus, stomach, pancreas, liver, gallbladder, small intestine, large intestine and anus

digest and absorb food and then excrete the waste product

Respiratory System Organs & Function

pharynx, larynx, trachea, bronchi and lungs

move fresh air into your body while removing waste gases

Excretory System Organs & Function

kidney, bladder, ureter, urethra, large intestine, liver, lung, skin

remove wastes from the body.

Muscular System Organs & Function

heart, digestive organs

Responsible for movement

Endocrine System Organs & Function

Pancreas, ovaries, testicles

coordinate your metabolism, growth, and development, and release hormones into the bloodstream.

Reproductive System Organs & Function

Women: ovaries, fallopian tubes, uterus, cervix, and vagina

Men: penis, testes and the scrotum

To produce egg and sperm cells.

Integumentary System Organs & Function

skin

protecting your body from bacteria, infection and injury

Nervous System Organs & Function

Brain, spinal cord,

sends messages back and forth between the brain and the body. The brain is what controls all the body's functions.

Skeletal System Organs & Function

Supports body movement and protects internal organs

goal of digestive system

digest our food and absorb molecules to provide nutrients and energy

Filter Feeding

filter food from large quantities of water.

Fluid Feeding

obtain their food from removing fluids from other organisms.

Gastrovascular Cavity

a tube with only one opening; food and waste enter/exit the same opening ex: jelly fish

Alimentary Canal

two openings; food enters one opening (mouth) and waste exits the other (anus) ex: earth worm

Mechanical Digestion

physical breakdown/movement of foods into smaller pieces (primarily carried out by the mouth and teeth)

Chemical Digestion

breakdown of food through chemicals (acids and enzymes) starting with saliva in the mouth

stages of digestion

Ingestion - the taking in of nutrients;

Digestion - the breakdown of food into smaller subunits;

Absorption - the transfer of the digested nutrients into the bloodstream; and

Egestion - the removal of waste products of digestion from the body.

Mouth

Site of mechanical digestion

Includes teeth, tongue, and saliva

Teeth: tear, cut, and mash food to break food down into smaller pieces

Tongue- moves food over teeth and has taste buds for tasting

Saliva- this starts before food even enters our mouth-salivary glands produce saliva which contains an amylase enzyme that digests starch into maltose (beginning of chemical digestion)

Esophagus

Bolus of food travels down the pharynx into the esophagus

The esophagus secretes mucin which lubricates it

Bolus moves down the esophagus through peristalsis

stomach

Muscular storage sac for food

Cardiac sphincter- controls entry of materials in and out of stomach

Rugae- ridges on inner lining of stomach that help with mixing of food

Muscles work together to mix and churn food with digestive juices

Pyloric sphincter- circular valve at base of stomach that controls exit of materials

gastric juices in the stomach

hydrochloric acid (HCI): kills microorganisms in our food and helps with further chemical digestion

pepsin - enzyme that begins protein digestion

mucus- this slimy secretion is produced by the stomach lining cells to protect the stomach itself from the gastric juices

Small Intestine

The chyme ( partially digested food) enters the small intestine from the stomach.

three main sections of small intestine

duodenum - 25-30 cm long

jejunum - 300 cm long

ileum - 400 cm long

duodenum

majority of chemical digestion occurs here using enzymes secreted by the pancreas and by glands in the wall of the intestine

jejunum

chemical digestion is completed here and some absorption occurs

ileum

absorption mainly occurs here

Large Intestine (colon)

• 1.5 m long with 4 main sections: ascending colon, transverse colon, descending colon and sigmoid colon.

• rectum stores solid waste temporarily.

• anus is a sphincter valve.

• caecum is a blind end sac where small intestine leads into the colon

• appendix is a tiny extension from the caecum (can become infected easily and has to be removed)

main functions of the colon

Recover water into the bloodstream and form solid feces.

Form/absorb certain vitamins (eg. Vitamin K & B)

Liver

• main function is to produce bile.

• Bile is an emulsifying agent which helps to spread fats over a wide surface

• Bile is transported through the hepatic duct.

Gallbladder

• storage sac which holds bile from the liver.

• bile salts can crystalize and form "stones" -called gallstones - which can block the bile duct.

Pancreas

produces a variety of digestive enzymes and secretes them through the pancreatic duct into the duodenum.

functions of the circulatory system:

• transport oxygen and carbon dioxide

• distribute nutrients and transport metabolic wastes

• help maintain the body temperature

• circulate hormones

Transport in Unicellular Organisms

• do not require a specialized transport system

• entire cell has access to the surrounding environment.

• "streaming" (moving cytoplasm) allows substances to be distributed throughout the cell.

Transport in Small Multicellular Organisms

• do not require a specialized transport system.

• fluid is taken in through the mouth and enters a body cavity that extends through most of the organism.

• materials are exchanged directly between the fluid and individual cells of the organism

Transport in Larger Multicellular Organisms

Substances are unable to diffuse or access all body cells quickly enough

two types of circulation systems

1. Open Transport Systems

2. Closed Transport Systems

Open Transport Systems

• Open system “hearts” are weak

• Blood does NOT stay in blood vessels but fills a body cavity

• Blood travels very slowly, and “sloshes around in the cavity

• Typically found in insects, where blood does not distribute oxygen to body tissues

• Nutrients in blood directly surround body cells and diffuse into cells

Closed Transport Systems

• closed system hearts pump blood strongly

• blood remains in blood vessels at all times

• nutrients in blood diffuse into the extracellular fluid where they are diffused into the cells

Types of Blood Vessels

• Arteries: Carry blood away from the heart

• Veins: Carry blood into the heart

• Capillaries: Connect arteries to veins, gas exchange drops off O2, picks up CO2

Pathway of Blood

• Lungs pick up oxygen

• Pulmonary Vein into the heart

• Through the Left Atrium and Ventricle pumped to the body

• Aorta-major artery out of heart

• Arteries path through the body

• Capillaries destination of oxygen, and carbon dioxide is picked up

• Veins take deoxygenated blood back to the heart

• Vena Cava's "blue" blood enters the heart

• Through the Right Atrium and Ventricle pumped to the lungs

• Pulmonary Artery "blue" blood heads to lungs

• Lungs-Drops off carbon dioxide

Plasma

• accounts for 55% of the blood volume

• 92% is water

• 7% are other blood proteins

• 1% are other nutrients and ions

Red Blood Cells (RBCs)

• Make up 44% of the total volume of blood

• Have no nucleus

• Main Role → Transport oxygen/CO2

• RBCs contain the molecule hemoglobin (which gives red colour)

• Oxygenated blood is bright red, deoxygenated blood is dark red.

White Blood Cells

• Makeup about 1% of blood volume

• This amount almost doubles when the body fights infection

• Leukocytes have a major role in the immune response

• have a nucleus and are colourless.

Platelets

• make up a very small portion of the blood.

• fragments of previously existing cells and break down quickly in the blood.

• No nucleus and lasts a week to ten days

• Their role in the blood is to aid in the blood clotting process.

Blood-Clotting

1. Blood vessel breaks and sends out a signal.

2. Platelets are attracted to the site of injury.

3. Platelets then rupture and release more chemicals.

4. Other agents will form certain enzymes and end with fibrin (from fibrinogen).

5. Fibrin forms a mesh of strands around the injury that trap blood cells and form a clot.

Tissues

a collection of similar cells that group together to perform a specialized function.

Gas Exchange

The basic functions of the respiratory (gas-exchange) system are to:

1. Provide each cell with O2

2. Allow each cell to eliminate CO2

Cellular respiration

The process where energy-containing molecules are broken down to release energy in a form the cell can use (ATP). Requires oxygen, forms carbon dioxide waste.

Gas Exchange

Cells take in oxygen and release carbon dioxide.

Breathing

The process of inhalation and exhalation - moving volumes of air into or out of the lungs.

Diffusion

used to move particles from an area of higher concentration to an area of lower concentration.

Site of Gas Exchange in Humans

Alveoli

Air Pathway: Starts from the mouth and nose.

Trachea (Windpipe): Air moves down through it.

Bronchi: Trachea divides into the right and left bronchi.

Bronchioles: Bronchi further divide into smaller branches called bronchioles.

Alveoli: Bronchioles terminate at alveoli.

Gas Exchange: Occurs at the alveoli.

Upper Respiratory Tract

Nasal Cavity- consists of nasal hairs, mucus, and blood vessels

Nasal hairs-trap dust and dirt to protect delicate lung tissue

Mucus- traps dirt and dust AND moistens the air to prevent the Jung tissue from dying (which will help diffusion occur quickly)

Blood Vessels- warm the air (diffusion is faster in warm air than in cold air)

Uvula-a flap of tissue hanging at the back of the mouth which closes when swallowing to prevent food and liquid from entering the nasal cavity

pharynx: the "throat" - an area where air and/or food & water pass

epiglottis: The flap of tissue which folds over the trachea when swallowing to prevent materials from entering the air passageways.

Lower Respiratory Tract

Larynx ("Voice Box"):

• Consists of two bands of tissue stretched across the opening of the trachea.

• Muscles Contract: Bring bands close together.

• Air Passing: Causes bands to vibrate, producing sound.

• Relaxed: Low sounds.

• Tightened: High sounds.

Alveoli: where gas exchange occurs

Lungs:

Humans have 2 lungs: one on the left and one on the right

The right lung has three lobes.

The left lung has two lobes.

Each lobe is divided into lobules, each with its own bronchiole.

ventilation

Definition: The process of air moving into the lungs and reaching the alveoli.

Breathing: a pressure differential must occur, air moves from an area of high pressure to low pressure.

Inhalation: pressure in lungs must be less than outside atmosphere.

Exhalation: pressure in lungs must be greater than outside atmosphere.

Mechanical Ventilation: Achieved by muscle contractions and relaxation. (muscles involved: Diaphragm and Intercostal Muscles)

genetics

the branch of biology dealing with the principles of variation and inheritance in organisms

Mendelian Genetics

refers to how traits are passed from parents to offspring

dominant

characteristics that are always expressed in an individual

recessive

characteristics that are latent (present but inactive) in an individual

heterozygous 

an individual who has two different alleles for a gene (ex: a girl has one dark allele and one blonde allele)

alleles

one form of a gene (usually two types for a gene)

(ex:Dark hair allele and blond allele)