NUTRITION IN PLANTS AND ANIMALS

Flashcards about nutrition in plants and animals, autotrophic and heterotrophic nutrition, photosynthesis, leaf structure and adaptation, factors affecting photosynthesis, chemical compounds of life, carbohydrates, lipids, proteins, enzymes, nutrition in animals, digestive system, vitamins, and minerals.

What is nutrition?

The process by which living organisms obtain and utilize nutrients.

What are the two types of nutrition?

Autotrophic and Heterotrophic.

What is Autotrophism?

Mode of nutrition in which a living organism manufactures its own complex food substances from simple substances.

Give examples of Autotrophs

Plants, algae and some bacteria.

What is Heterotrophism?

Is a mode of nutrition that involves taking in of already made complex food materials.

What are heterotrophs?

Organisms that feed on already made food.

What is Photosynthesis?

Manufacture of organic food materials from Carbon (IV) oxide and water, using sunlight.

What is Chemosynthesis?

Manufacture of organic compounds using chemical energy obtain from oxidation of inorganic compounds.

Why are green plants referred to as primary producers?

They carry out photosynthesis, producing carbohydrates, proteins and lipids which directly or indirectly act as a source of food for animals.

What is the source of organic compound (matter)?

Organic matter synthesized by green plants are consumed directly or indirectly by animals.

What is the source of atmospheric oxygen?

Oxygen is a by-product of photosynthesis, it is used by animals and other aerobic organisms for respiration.

What maintains the concentration of Carbon (IV) oxide in the atmosphere?

The carbon (IV) oxide produced by respiring organisms is utilized in the process of photosynthesis.

What is the external structure of a leaf?

A thin flattened organ attached to the stem or branch.

What is lamina?

The flattened surface of a leaf.

Why do leaves have broad and flat lamina?

To provide a large surface area for absorption of light energy for photosynthesis and diffusion of gases.

What is the advantage of thin lamina/blade in leaves?

To provide a short distance for the diffusion of carbon (IV) oxide to photosynthetic cells. Thinness also allows light to penetrate through and reach photosynthetic cells.

What is the function of leaf petiole/ sheath?

To provide an attachment of the leaf to the stem for maximum absorption of light.

What is the function of leaf veins?

Have xylem vessels and tracheids which conduct water and mineral salts to the photosynthetic / palisade cells; and phloem tissues for transportation of photosynthetic products.

What is a Cuticle?

Waxy substance that covers the upper and lower epidermis of a leaf.

Mention some attributes of the cuticle

Transparent to allow light to pass through, water proof and reduces rate of water loss and protects the inner tissues against entry of disease causing micro-organisms.

What are Stomata?

Small openings found on the leaf surface.

What is the function of stomata?

To allow carbon (IV) oxide to diffuse into the photosynthetic tissues and water vapour and oxygen out of the leaf during photosynthesis.

What is leaf arrangement (leaf mosaic)?

Arrangement of leaf on the plant to expose the leaf to receive maximum light.

What does leaf mosaic prevent?

Prevents overlapping and overshadowing.

Describe the epidermis of a leaf

Upper and lower epidermis covered by a transparent cuticle, thin and transparent to allow light to penetrate into the leaf.

What is function of Guard cells?

Regulates movement of gases, have chloroplasts for photosynthesis.

Describe Palisade mesophyll

Made of closely packed cells that are vertically elongated to enable them receive maximum light and contain numerous chloroplasts to provide a large surface area to trap maximum light for photosynthesis.

What are the attributes of the Spongy mesophyll layer?

Irregularly shaped and loosely arranged cells with intercellular spaces to create large space for air circulation, for maximum diffusion of gases between the cells.

What is a chloroplast?

It is a disc-shaped organelle inside the palisade, guard cell and some spongy mesophyll cells. It is the site for photosynthesis.

What is contained in the stroma?

The stroma contains enzymes that speed up the rate of photosynthesis.

What is the function of the grana?

Membrane of the grana provide a large surface area for packaging of chlorophyll.

What are the two stages of photosynthesis?

Light stage and dark stage.

What is the main product of photosynthesis?

Glucose.

What are the raw materials of photosynthesis?

Water and carbon (IV) oxide.

Where does the Light independent stage of Photosynthesis occur?

Occurs in the granum of chloroplast in presence of light.

Where does the Light independent stage of Photosynthesis occur?

Occurs in the stroma of chloroplast in absence of light.

What happens during the light independent stage of photosynthesis?

Hydrogen atoms combine with carbon (IV) oxide in presence of ATP and enzymes to form glucose.

What are the usages of glucose formed during photosynthesis?

Some enter mitochondrion for respiration to produce energy, some can be converted into cellulose for formation of cell walls and some is converted into starch and stored in the starch granules in the chloroplast.

What are the factors affecting photosynthesis?

Light intensity wavelength and duration, carbon dioxide concentration, temperature, water availability and availability of mineral salts.

What is the role of Light intensity?

Light provides energy for process of photosynthesis.

How does the rate of photosynthesis vary with increase the light intensity?

Increase in light intensity increases the rate of ATP synthesis and photolysis hence more ATP and hydrogen atoms are provided for photosynthesis.

What happens to the rate of photosynthesis at optimum conditions?

The rate of photosynthesis remains constant and the graph levels off. Further increase in light intensity above optimum does not affect the rate of photosynthesis.

What happens to chlorophyll at very high light intensity?

Chlorophyll is damaged and the rate of photosynthesis falls.

Which wavelengths are absorbed by chlorophyll and used for photosynthesis?

Red and Blue.

What is Light duration/ photoperiodism?

Refers to the length of time per day when there is light.

What is Carbon (IV) concentration in the atmosphere?

Relatively constant at about 0.03%.

How does increase in carbon (IV) oxide affect the rate of photosynthesis?

An increase in carbon (IV) oxide concentration leads to an increase in the rate of photosynthesis up to an optimum level. Any further increase in Carbon (IV) concentration has no effect on the rate of photosynthesis.

What is the optimum carbon (IV) oxide concentration?

For photosynthesis is about 0.1%.

What happens when carbon (IV) oxide concentration above 5%?

Could damage the plant.

How does temperature affect photosynthesis?

Temperature affects photosynthetic enzymes.

How does low temperature affect the rate of photosynthesis?

Low temperature below optimum results to low rate of photosynthesis, because enzymes are inactive.

How does increase in temperature beyond optimum, affect rate of photosynthesis?

Further increase in temperature beyond optimum, results to a decrease in rate of photosynthesis because enzymes are denatured.

How does water availability affect photosynthesis?

Plants that grow in water deficiency environment, may photosynthesize at low rate.

What other plant activities are made possibly by water?

Turgidity of guard cells, which controls opening and closing of stomata.

Which minerals salts are required in synthesis of chlorophyll?

Magnesium, manganese and nitrogen.

What are the internal factors affecting photosynthesis?

Leaf age, leaf surface area exposed to the environment, chlorophyll content in the leaves, accumulation of photosynthetic products and the number and nature of stomata to let carbon (IV) oxide in the leaf whether they are opened or closed.

Why is the leaf first boiled in hot water in the test to investigate the presence of starch in a leaf?

To kill all the cells and stop all the chemical reactions taking place in the leaf, and also to make it soft/ to break the starch granules.

Why is the leaf boiled in alcohol or methylated spirit in the test to investigate the presence of starch in a leaf?

To dissolve chlorophyll and other pigments, process called bleaching, it makes it easy to observe any colour changes on the leaf.

Why is it necessary to dip the leaf in hot water after boiling it in alcohol/methylated spirit.?

In order to soften it, and rinse off excess methylated spirit from the leaf.

Why is the plant is placed in a dark place for 48 hours in the test to show that Light is necessary for the process of photosynthesis?

To ensure that all the starch present in the leaves is used up.

What is the function of the sodium hydroxide in the test to show Carbon (IV) oxide is necessary for photosynthesis

Absorbs carbon (IV) oxide in the flask.

What is a compound?

A compound is a substance that is made up of two or more different elements.

What are the types of compounds?

Organic and inorganic.

Give examples of organic compounds?

Carbohydrates, proteins, lipids, and vitamins.

Give examples of inorganic compounds?

Mineral salts, water, acids and bases.

What is biochemistry?

The study of chemical compounds in living organisms and their reactions in the body.

What are carbohydrates?

Bio-chemicals composed of carbon, hydrogen and oxygen in the ratio 1:2:1 respectively.

What are the main types of carbohydrates?

Monosaccharide, Disaccharide and Polysaccharide.

What are Monosaccharides?

The simplest carbohydrates with the general formula (CH2O)n; where n=6.

Mention some common monosaccharides

Glucose, Fructose and Galactose.

What are the functions of monosaccharide?

Energy production and they are the building blocks of more complex carbohydrates.

What are disaccharides?

Sugars that are made up of 2 monosaccharide units.

How are disaccharides formed?

When 2 molecules of monosaccharides are linked together by a process called condensation, giving a molecule of H2O.

What is the general formula for Disaccharides?

C12H22O11.

Mention some examples of disaccharides products.

Glucose + Glucose →Maltose + water, Glucose + Fructose→ Sucrose + water and Glucose + Galactose→ Lactose + water.

What kind of bond does Condensation involve?

Involves the formation of a chemical bond called Glycosidic bond.

What are some functions of disaccharides?

Are hydrolysed by enzymes into monosaccharides which are then oxidised in the mitochondrion to release energy for the cell.

What are Polysaccharides?

The most complex carbohydrates.

How are polysaccharides formed?

When very many monosaccharides are condensed together and linked by Glycosidic bond.

What is the general formula for polysaccharides?

(C6H10O5) n where n represents a big number of monosaccharide units making the polysaccharide e.g. 1000.

Mention some common types of polysaccharides

Starch, cellulose, lignin, glycogen and chitin.

What is the importance of Starch?

It is the storage form of carbohydrates in plants.

What is the importance of Cellulose?

It is fibrous, tough and insoluble in water, it forms the framework of cell walls in plants and fungi and in animals, cellulose acts as roughage in diet, It eases movement of food along alimentary canal.

What is the importance of Glycogen?

This is the storage form of carbohydrates in the animal body.

What are the properties of polysaccharides?

Insoluble in water, do not have sweet taste and they are non-reducing sugars.

Mention sources of energy in polysaccharides

They are hydrolysed into monosaccharides that become respired to provide energy to the cell.

What are lipids?

Lipids are fats and oils.

What are lipids formed of?

Compounds of carbon, hydrogen and oxygen.

What are fats?

Solid at room temperature and are found in animals e.g. cheese, butter.

What are oils?

Liquid at room temperature and are found in plants e.g. coconut oil, sunflower oil.

Of what molecules are lipids made?

Glycerol and fatty acids joined together by ester bond through condensation process.

Mention some complex lipids

Phospholipids, Steroids and Waxes.

What are Phospholipids?

Are components of cell membranes.

Of what molecules are phospholipid made?

Are components of cell membrane and made up of phospholipid bilayer.

State some attributes of Steroids

The most common sterol is cholesterol, and many human hormones are steroids and have a cholesterol-like structure, e.g. Testosterone, Oestrogen, Progesterone, aldosterone, and adrenaline.

Give some examples of waxes

Examples are beeswax, ear wax, wax in the cuticle.

Mention the functions of lipids

Source of energy, source of metabolic water, heat insulation, protection and structural component.

How do lipids act as a source of energy?

Release twice as much energy as released by carbohydrates per unit weight.

How do lipids act as source of metabolic water?

Release much water, this water helps desert animals e.g. camels to survive longer.

Why are Proteins referred to as nitrogenous compounds?

Proteins are referred to as nitrogenous compounds because of presence of nitrogen in their structures.