Biology Cape Unit 1

Describe the structure of water.

The water molecule is made up of two atoms of hydrogen covalently bonded to one atom of oxygen.

The explanation for water's property of a good solvent for charged substances and uncharged substances though less readily for the latter

Due to the dipole or charge separation, polar molecules (such as glucose) and ions are charged and are attracted to the weak charges on water molecules

The role of water as a solvent explanation in organisms and environment

In organisms it acts as a solvent within cells, solvent in transport media for example blood plasma, lymph, phloem, and xylem saps

In the environment it acts as a solvent for nutrients and gases (carbon dioxide and oxygen) where carbon dioxide is much more soluble than oxygen

Explanation for the property of water where it has a high specific heat capacity

4.2 J are necessary to increase the temperature of 1 gram of water by 1 degree Celsius. This thermal energy breaks hydrogen bonds between water molecules

Roles of water in organisms and the environment in terms of heat capacity

The specific heat capacity of water is higher than that of other common substances. This limits fluctuations in the temperature of organisms and the environment of those that live in water

Explanation for the water property of high latent heat of vaporization

Much thermal energy is needed to cause water to change into water vapour

Role of water in terms of high heat of vaporization for organisms

Loss of water for cooling (such as in transpiration and sweating) is efficient as a lot of thermal energy is needed to evaporate small quantities of water

Role of water in terms of heat of vaporization for the environment

Water in shallow aquatic habitats (such as ponds, rock pools) does not evaporate too quickly

Explanation for the property of water of a high latent heat of fusion

Much thermal energy is needed to change ice into water and much is transferred from water when it forms ice

Role of water in terms of latent heat of fusion for the organisms

Water in cells tends to stay as a liquid so cell membranes are not damaged by ice crystals

Explanation for the property of water where it is described as reactive

Water splits to form hydrogen and hydroxide ions

Explanation for water's density

Ice is less dense than water to due to its bonds separating from each

Role of water in terms of reactivity within organisms

Water acts as raw material for photosynthesis, it provides hydrogen ions and electrons for photosynthesis and respiration. It is also used in hydrolysis reactions for example digestion

The roles of water in organisms in terms of density

Ice that forms in cells breaks cell membranes and kills cells. Organisms at risk of freezing make anti-freeze compounds that lower the freezing point of cytoplasm

The roles of water in the environment in terms of density

Provides buoyancy for aquatic organisms so do not need highly developed skeleton

Ice floats on water thus acting as an insulation for aquatic organisms beneath

The explanation of the in-compressible property of water

Water cannot be compressed into a smaller volume

The roles of water in organisms in terms of in-compression

Hydro-static skeleton in animals (such as anemones and worms)

Turgidity in plant cells which provides suppot

Explanation of water's high cohesion

Hydrogen bonds hold water molecules together

Roles of water in organisms in terms of high cohesion

Supports columns of water in Xylem

Roles of water in the environment in terms of high cohesion

Gives surface tension allowing some organisms to live on the surface of water

How much do animals consist of water

Animals consist of 70 percent of the bodies of animals

Why does water differ from other hydrogen compounds of other group 6 elements

This is due to it's excessive hydrogen bonding

The effects of hydrogen bonding in water

Slightly negative oxygen and slightly positive hydrogen resulting in a dipole molecule

A week force of attraction (one tenth that of covalent bonding) easily broken which they do and reform all the time

Sticky water molecules

How much do plants consist of water

Plants consist of 90 percent of water

From where did life evolve from?

Water

THe most common colour in the environment

Green- The colour of chlorophyll, the main photosynthetic pigment in plants

The use of chlorophyll

It is used to absorb light and is involved in the conversion of light energy to chemical energy and as such is the basis of life. It is an energy transducer(converts energy from one form to another)

Location of chlorophyll

Inside chloroplasts which are found in organelles found within plant cells.

Biochemistry

The study of biological molecules and their roles in organisms. These molecules are the building blocks of life-constantly being assembled and taken apart.

Metabolism

The term given to all the chemical reactions that occur in organisms

Types of metabolic reactions

Catabolic and anabolic reactions

Definition of catabolism

The reactions that break down large biological molecules into smaller ones

What all the major compounds that make up organisms consist of:

The element carbon

Common functions of biological molecules

Provide energy, carry messages, catalyze reactions, store energy, store and retrieve information and transport gases

Complex compound of carbon

Organic compounds

Chemical element

Pure chemical substance consisting of one type of atom

Atom

Smallest component of an element having the chemical properties of the element; the nucleus of an atom consists of neutrons and protons, it is surrounded by electrons

Isotope

Atoms of the same element with different numbers of neutrons in the nucleus.

Compound

A substance made from two or more chemical elements

Molecule

The smallest particle of a substance that retains the chemical and physical properties of the substance and is composed of two or more atoms.

Ion

An atom or molecule or chemical group that has lost or gained one or more electrons and is either positively or negatively charged.

Ionic bond

Chemical bond between two ions with opposite charges.

Covalent bond

A chemical bond involving the sharing of a pair of electrons between atoms in a molecule

Monomers

The small molecules

Polymers

Large molecules consisting of smaller ones

Elements carbohydrates consist of

Carbon, hydrogen, oxygen in a ratio of 1:2:1

Elements lipids consist of

Carbon, hydrogen and oxygen in ratio of approximately 1:2 (C:H), 9:1 (C:O) and 18:1 (H:O)

Elements proteins consist of

C,H, O, N, S

Elements nucleic acids consists

C,H,O,N,P

Sub-unit of carbohydrates

Glucose

Sub-unit of lipids

Glycerol and fatty acids

Phosphate (Phospholipids)

Sub-unit molecules of proteins

Amino acids (20 different types)

Sub-unit of nucleic acids

Nucleotides (five different types)

Examples of carbohydrates

Starch (Amylose and amylopectin)

Glycogen

Cellulose

Examples of lipids

Triglycerides and phospholipids

Examples of proteins

Haemoglobin, collagen, amylase, pepsin, insulin and antibodies

Examples of nucleic acids

DNA, RNA (mRNA, rRNA, rRNA)

Roles in organisms of carbohydrates

Energy storage and support

roles in organisms of lipids

Energy storage, thermal insulation, electrical insulation and membranes

The role of proteins in organisms

Transport, support, catalysts, messengers, protection

The role of nucleic acids in organisms

Information storage, information retrieval and production of proteins

The properties of the organic compound carbohydrates

Contain elements carbon, hydrogen and oxygen

They have a general formula Cx(H2O)y

They include monosaccharides (such as glucose), disaccharides (such as sucrose) and polysaccharides (such as starch,glycogen and cullulose)

Possible number of carbon atoms in monosaccharides (x in Cx)

four,five,six or seven

Shapes glucose molecules take or exist as

Rings (most often) and straight chains

What two ring forms are dependent on

-H and -OH groups about the carbon atom at position 1

Forms of glucose molecules

alpha and beta with the -OH molecule being below the ring and above the ring respectively

Structure of glucose (description) and thus its functions

It has six carbon atoms as a hexose sugar. It is a polar molecule and thus is water soluble. It is the form of carbohydrate that is transported in the blood of animals because it is readily taken up by cells and are metabolized to:

Provide a source of energy in respiration

be polymerized to form a polysaccharide for energy storage

Used as a raw material to make other compunds for example disaccharides

Common general sugars

Hexoses, pentoses (five carbon atoms) and trioses (three carbon atoms)

Definition of disaccharides

This is the compound formed when two monosaccharides join together to form complex sugars

Describe the formation of sucrose

In the reaction a water molecule is removed so that an oxygen "bridge" forms between carbon 1 of the glucose molecule and carbon2 of the fructose molecule. The bond that forms is a glycosidic bond, a strong covalent bond

The reaction that creates disaccharides

Condensation reaction because water is formed

Draw the structure of beta glucose.

...

Draw the structure of alpha glucose.

...

What are the functions of glucose?

Glucose is used as an energy source, a transport substance and a monomer to make other organic substances.

How does the structure of glucose enable it to be a good source of energy?

It's carbon atoms are easily oxidized to form carbon dioxide releasing energy in the process.

How does the structure of glucose enable it to be a good transport substance?

The numerous hydroxyl groups in glucose allows it to hydrogen bond with water molecules, thus making it highly soluble in water.

How does the structure of glucose enable it to be a monomer to make other organic substances?

The aldehyde group in glucose is very reactive so it will easily polymerize.

Describe the structure of the sucrose molecule and draw it.

A sucrose molecule is made up of an alpha glucose molecule linked to a beta fructose molecule by a 1-2 glycosidic bond.

What are the functions of sucrose?

Sucrose is used as an energy source, a transporter and a storage material in some plants.

How does the structure of sucrose enables it to be a good energy source?

The enzyme sucrase hydrolyzes sucrose to glucose and fructose since it is unreactive. The fructose molecule is then rearranged to form glucose.

Characteristics of sucrose

Sucrose is polar, water soluble, not as reactive as glucose and fructose as the aldehyde and the ketone groups form the glycosidic bond and are not available to react (non-reducing sugar)

It is an advantage for sucrose to be a less-reactive sugar for transport in plants

The transport is slower in plants than in animals

Definition of hydrolysis reaction

The addition of water to break a glycosidic bond

How does the structure of sucrose enable it to be a good storage molecule and a good transport substance ?

The aldehyde group and the ketone group are linked together in the glycosidic bond, thus has no reactive group.

Draw the molecular structure of starch.

...

Definition of Polysaccharides

Substances consisting of many monomers (monassacharides)

Describe the formation of a polyssacharide

Glycosidic bonds that form between carbon 1 at the end of the growing chain and carbon 4 of the glucose monoer that is being added are knowkn as 1,4 glycosidic bonds. A branching point is formed by adding a glucose monomer to carbon 6 on a growing chain. The type of glycosidic bond that forms to make these branching points is 1,6 glycosidic bonds. From the first monomer added another chain can form with more 1,4 glycosidic bonds joining glucose monomers together

Three energy storage polysaccharides

Amylose, amylopection and glycogen

Forms of starch

Amylose and Amylopectin

Describe glycogen

Similar to amylopectin but it has moe 1,6 glycosidic bonds than amylopectin and therefore many more branches

Another name for glycogen

Animal starch

Definition of cellulose

This is a long chain made from Beta glucose monomers. It is it is the most common biological compound on earth and it is not used for energy storage but for making the cell walls of plants

What makes the three energy storage polyssacharides

Alpha glucose molecules

What is starch made up of and what are the types of bonds?

Starch is a mixture of amylose and amylopectin joined together by an alpha 1-4 glycosidic bond. Amylopectin has alpha 1-6 branches which spirals to a lesser extent than the unbranched amylose which coils up into a spiral.

Why is starch insoluble?

Starch is made up of 79% amylopectin. Amylopectin has branched chains and the more branched chains it has, the more insoluble it is.

How does the structure of starch enable to be a good energy reserve?

The enzyme amylase can break down starch into glucose molecules and since it coils to form spirals, it is more compact.

Draw the molecular structure of glycogen.

...

Name the types of bonds in glycogen and the and what it is made up of?

Glycogen is made up of alpha glucose. It is made up of alpha 1-4 glycosidic bonds with alpha 1-6 branches.

Why is that glycogen so dense?

It has more branches than amylopectin so it is heavily branched, so it is less able to form spirals

Role of glycogen

Energy storage in animals, fungi and some bacteria