V Biology EOY

Structure of the Thorax

Intercostal Muscles in Inhalation

contract

Intercostal Muscles in Exhalation

Relax

Diaphragm in Inhalation

Muscles contract: diaphragm raised

Diaphragm in Exhalation

Muscles: relax - diaphragm lowers

Alveoli Adaptations

• Large SA: More oxygen/CO2 can diffuse per second

• Thin barrier: Short diffusion distance - walls 1 cell thick

• Large network of capillaries: maintains a high concentration gradient

• Moist lining: so gases can dissolve

• Ventilation: Allows the organism to maintain a concentration gradient

3 Main Components of Cigarettes

• Nicotine

• Tar

• Carbon Monoxide

Biological consequences of Smoking

• Mimics action of neurotransmitters at synapses and makes smoker feel more alert

• Stimulates the release of adrenaline (increase heart rate etc.)

• Settles on lining of airways and alveoli:

  • Increases diffusion distance

  • Chemicals cause muscles to contract narrowing airways

  • Cause excess mucus production

• Combines with haemoglobin irreversibly:

  • Reduces oxygen carrying of blood

  • Damages lining of arteries

Coronary heart disease from Smoking

• Chronic Bronchitis: Overproduction of mucus and inflimation of lining of airways

• Emphysema: Cause alveoli to burst

• Lung Cancer

Names of different trophic levels:

1. Producer

2. Primary consumer

3. Secondary consumer

4. Tertiary consumer

5. Apex predator

6. Decomposers

Producer

An organism that makes its own food via photosynthesis

Consumer

An organism that retrieves its energy from consuming another organism

Decomposer

An organism that breaks down organic material such as the remains of a dead organism

Pyramids of Number

Total number of each organism at each trophic level

Pyramids of Biomass

Total dry mass of each organism at each trophic level

Why is only 10% of energy transferred from one trophic level to the next?

• Not all of the materials are transferred from one level to the next (bones are not eaten etc.)

• Some parts of the organism are not digested so not absorbed

• Some of the materials absorbed form excretory products

• Many are respired to release energy - loss of CO2, water and thermal energy

Why can unicellular organisms rely on diffusion for movement of substances in and out of the cell?

Unicellular organisms have very large SA : V ratio meaning that the distance between the surface of the organism to its centre is very small

Why do multicellular organisms need a transport system?

• They consist of many cells that differentiate to take on specialized functions.

• They have a small surface area to volume ratio, so transport systems are needed to get substances to the correct place.

• Transport systems supply cells with useful substances (e.g. glucose and oxygen) and remove waste products.

• Eg. Circulatory system in humans

Composition of Blood

Red blood cells, White blood cells, Platelets and Plasma

The Role of Plasma

Transporting dissolved carbon dioxide, digested food molecules, urea and hormones; distributing heat

Adaptations of Red Blood cells so they are suitable for the transport of oxygen

• Contain haemoglobin: Haemoglobin can combine reversibly with oxygen. This means that it can combine with oxygen as blood passes through the lungs, and release the oxygen when it reaches the cells.

• They have no nucleus so they can contain more haemoglobin.

• They are small and flexible so that they can fit through narrow blood capillaries.

• They have a biconcave shape to maximise their surface area for oxygen absorption.

• They are thin, so there is only a short distance for the oxygen to diffuse to reach the centre of the cell.

Phagocytes

Engulf and destroy unwanted microorganisms that enter the blood, by the process of phagocytosis.

(Part of the immune system)

Lymphocytes

Produce antibodies when a foreign body such as a microorganism enters the body:

• they bind to pathogens and damage or destroy them

• they coat pathogens, clumping them together so that they are easily ingested by phagocytes

• they bind to the pathogens and release chemical signals to attract more phagocytes

Lymphocytes may also release antitoxins that stick to the toxins that the microorganism makes, which stops it damaging the body.

(Part of the immune system)

How do vaccines work?

Allow a dead or altered form of the disease causing pathogen to be introduced into the body, which contain a specific antigen. This causes the immune system, specifically the white blood cells, to produce complementary antibodies, which target and attach to the antigen.

Platelets

• They have proteins on their surface that enable them to stick to breaks in a blood vessel and clump together

• They secrete proteins that result in a series of chemical reactions that make blood clot, which plugs a wound

Structure of the Heart

How and what factors may increase the risk of developing coronary heart disease?

• poor diet – eating more saturated fat tends to increase cholesterol levels

• stress and smoking – increases blood pressure

• salt – eating too much causes high blood pressure

• lack of exercise

• genetic factors

Arteries: Adaptations

• Have thick muscular and elastic walls to accommodate and pump blood and withstand high pressures and stretch + recoil

• Have connective tissue to provide strength

Veins: Adaptations

• Have thin walls

• Have valves to prevent backflow of blood

• Large lumen as there are low pressures

Capillaries: Adaptations

• Walls one cell thick: therefore allow the exchange of molecules between the blood and the body's cells - molecules can diffuse across their walls

General structure of circulation system

Production of ATP is via:

Process of Respiration

What does ATP provide for cells?

Energy

Aerobic Respiration

Occurs with the use of Oxygen

Anaerobic Respiration

Occurs when Oxygen is not present

Word Equation for Aerobic Respiration

glucose + oxygen → carbon dioxide + water (+ energy)

Balanced Chemical Equation for Aerobic Respiration

C6H12O6 + 6O2 → 6CO2 + 6H20

Word Equation for Anaerobic Respiration

glucose → lactic acid (+ energy)

Mitochondria

Aerobic respiration

Nucleus

Contains DNA

Ribosome

Protein synthesis

Cytoplasm

Many chemical reactions

Cell membrane

Controls what enters and leaves

Cell wall

Support and strength

Vacuole

Contains cell sap

Chloroplast

Photosynthesis/ Absorbs light

carbohydrate elements

carbon, hydrogen and oxygen (CHO)

lipid elements

carbon, hydrogen, oxygen (CHO)

protein elements

carbon, hydrogen, oxygen, nitrogen (CHON)

storage for carbohydrates in: plants

starch: polysaccharide

storage for carbohydrates in: animals

glycogen: made of glucose (monosaccharide)

lipids are made of:

fatty acids and glycerol (meaning they are triglycerides)

proteins are made of:

long chains of amino acid monomers (meaning they are polymers)

test for: starch

iodine: brown → blue

test for: glucose

benedicts test: blue → brick red

test for: lipids

ethanol emulsion: white emulsion

test for: proteins

biruet: blue → lilac

Word equation for Photosynthesis

carbon dioxide + water —> glucose + oxygen

Balanced chemical equation for Photosynthesis

6CO2 + 6H2O —> C6H12O6 + 6O2

The process of Photosynthesis

• Light energy is used to split water, releasing oxygen gas and hydrogen ions.

• Carbon dioxide gas combines with the hydrogen to make glucose.

This is important in order for the plant to maintain/ gain energy and continue to grow

Use of Magnesium Ions

Chlorophyll

Magnesium Deficiency

Plant leaves appear yellow

Use of Nitrate Ions

Amino acids

Nitrate Deficiency

Poor growth and yellow leaves

Use of Mineral Ions

Growth

Bioaccumulation

Bioaccumulation occurs when toxins build up - or accumulate - in a food chain. The animals at the top of the food chain are affected most severely.

Biomagnification

The rise or increase in the contaminated substances caused by the intoxicating environment.

Causes of Eutrophication

Some pollutants affect the environment by disrupting the equilibrium in food chains:

• Sewage

• Nitrate Fertilisers

• Pesticides

Adaptations of the leaf for Photosynthesis

Adaption	Large surface area
Purpose	To absorb more light

Adaption	Thin
Purpose	Short distance for carbon dioxide to diffuse into leaf cells

Adaption	Chlorophyll
Purpose	Absorbs sunlight to transfer energy into chemicals

Adaption	Network of veins
Purpose	To support the leaf and transport water, mineral ions and sucrose (sugar)

Adaption	Stomata
Purpose	Allow carbon dioxide to diffuse into the leaf and oxygen to diffuse out

Adaption	Epidermis is thin and transparent
Purpose	To allow more light to reach the palisade cells

Adaption	Thin cuticle made of wax
Purpose	To protect the leaf from infection and prevent water loss without blocking out light

Adaption	Palisade cell layer at top of leaf
Purpose	To absorb more light and increase the rate of photosynthesis

Adaption	Spongy layer
Purpose	Air spaces allow gases to diffuse through the leaf

Adaption	Palisade cells contain many chloroplasts
Purpose	To absorb all the available light

Effect of Carbon Dioxide on rate of photosynthesis

Effect of Temperature on rate of photosynthesis

Effect of Light Intesity on rate of photosynthesis

Root hair cell adaptations

• Elongated: large surface area

• Short diffusion distance because the wall is one cell thick

• Lots of mitochondria for respiration to release ATP for active transport

Absorption of water into plants by root hair cells

The water in the soil diffuses into the roots by osmosis from an area of high water concentration to a low water concentration across a partially permeable membrane and travels up the roots into the stem and travels up the stem into the leaves.

Absorption of mineral ions into plants by root hair cells

The mineral ions move from an area of low concentration to an area of high concentration across a partially permeable membrane using ATP from respiration into the roots via active transport and travels through the roots and stem into the leaves.

Role of the Xylem

Water and dissolved mineral ions travel in these vessels from root to shoots and leaves in one direction.

Xylem Vessels

Have thick cellulose cell walls, strengthened by lignin. Once xylem cells have formed the xylem, they die making long, thin, hollow vessels for water to move through. The thick walls also help support plants.

Role of the Phloem

Carries dissolved sucrose and amino acids from the leaves to the growing and storage parts of the plants. Transports sucrose up the plants from stores of starch e.g. in root tubes.

Phloem cells

These cells are alive - if they are damaged they cannot work properly. Phloem are made of companion cells and sieves. Cells are joined by small tubes in the cell wall at the end of each cell, forming a continuous system. The end walls are called sieve plates.

Sieve tubes

Nearly empty - allow sap (sucrose) to move easily

Companion cells

Have normal cell contents including lots of mitochondria

Transpiration

The loss of water by evaporation from the plants - they lose water when they open the stomata in the leaves for gas exchange.

Stomata

Small holes located on the underside of the leaves to allow for the exchange of gases. Water also evaporates through the stomata.

Guard cells

Each stoma is surrounded by two guard cells, which control the opening and closing of the stoma. The guard cells gain water and become more turgid. They curve out opening the stoma and allowing gases in and out.

Stage 1 of the Opening of the Stomata

Accumulate solutes in their vacuoles which lowers the water potential. Water moves in by osmosis. The guard cells swell up which changes their shape - opening the stomata.

Stage 2 of the Opening of the Stomata

The stomata are open for gas exchange. During this time water is lost as water vapour moves out of the leaf down the water potential gradient.

Stage 3 of the Opening of the Stomata

At night the guard cells lose water so becoming flaccid and close the stomata.

Closing at Night is a Useful Adaptation because:

The guard cells are the only cells in the lower epidermis to contain chloroplasts and so the opening and closing of  the stomata is caused by light intensity.

• There is no light so no need for photosynthesis

• No need to cool the plant

Stage 1 of the Transpiration Stream

Water leaves the cells of the mesophyll and evaporates into the air spaces. This water vapour diffuses out through the stomata down the water vapour potential gradient

Stage 2 of the Transpiration Stream

The loss of water from the mesophyll cells reduces the water potential of these cells so water moves by osmosis from the surrounding cells into these cells down the water potential gradient.

Stage 3 of the Transpiration Stream

Water from the xylem moves into the mesophyll cells down the water potential gradient.

Stage 4 of the Transpiration Stream

The loss of water from the xylem causes water to be pulled up the xylem in the stem and the roots in a continuous flow, called the ‘transpiration stream’

Transpiration stream functions

• Supplies water to the palisade mesophyll for photosynthesis

• Carries mineral ions dissolved in the water to cells in the plants

• Provides water to cells to keep cells turgid

• Allows evaporation from the leaf surface, which cools the leaf in a similar way to sweating cooling the skin

Effect of Light Intensity on the Rate of Transpiration

The rate of transpiration increases as light intensity increases because of the opening of the stomata for gas exchange for photosynthesis

Effect of Temperature on the Rate of Transpiration

Higher temperatures increase the rate of transpiration by increasing the rate of evaporation from the mesophyll cells

Effect of Wind Speed on the Rate of Transpiration

The rate of transpiration increases with faster air movements across the surface of the leaf as the moving air removes any water vapour which might have been near the stomata so increasing the water vapour potential gradient

Effect of Humidity on the Rate of Transpiration

The rate of transpiration is higher when the air is less humid as there is an increased water vapour potential gradient.

Organ

A collection of tissues that work together to perform a particular function

Nervous System

Uses electrical impulses for faster, shorter lined responses

Endocrine System

Uses hormones for longer lasting and slower responses