Holozoic Nutrition: Steps

Holozoic Nutrition: Steps

1.      Ingestion

2.      Digestion

3.      Absorption

4.      Assimilation

5.      Egestion

Ingestion: it is the process of intake of food. Ingestion depends on the size of food and the structure of organ adapted of the ingestion of food. The different organisms have different features to ingest, like amoeba ingest through pseudopodia. Paramecium has cilia, hydra has tentacles, insect use their mouth parts and humans use their mouth.

Digestion: It is the process of breaking down of large sized, complex food that is insoluble and non-diffusible. digestion is a catabolic process. The ingested food is in form of protein, carbohydrates and fats, these are organic polymer compounds. When this food breaks in simpler form, which is soluble and diffusible. The protein converts in amino acids, carbohydrates in form of glucose and fats into fatty acids, these are organic monomer compounds. This breakdown takes place in presence of digestive enzymes that are in digestive juices which are secreted by the digestive glands. Digestion is basically of two types: intracellular digestion and intercellular digestion.  Intracellular digestion takes place inside the cell. This takes place generally in case of lower organisms. Eg; sponges, protozoa, amoeba. .  Intercellular digestion takes place inside the alimentary canal. This takes place generally in case of higher organisms. Eg; human beings

Absorption: it is the process of absorption of diffusible nutrient through the wall of alimentary canal of small intestine. This absorbed food goes in the blood and lymph. Generally the absorption is of two types: physical absorption and active absorption. Physical absorption involves diffusion or osmosis of nutrients whereas active transport involves movement of nutrient through the medium.

Assimilation: it is an anabolic process in which the food that is broken down as simple nutrient gets converted into complex bio molecule inside the cell these polysaccharides helps in the growth and repair of tissue.

Egestion: this is the process of expelling of undigested food in form of faeces. The excess of water, undigested enzymes comprises the faeces. The roughage adds bulk to faeces.

Exchange of Gases in plants

Exchange of gases in plants, Diffusion, Opening and Closing of Stomata, structure of stomata, endosmois, exosmosis

Exchange of gases in plants

Exchange of gases is an important phenomenon that is essential for physiological processes like photosynthesis and respiration. Oxygen is released and carbon dioxide is absorbed in Photosynthesis and in respiration of plants carbon dioxide is released and oxygen and absorbed. Although, like animals plants do not posses any special respiratory organs but this exchange of gases take place by the process of diffusion.

Diffusion is the movement of molecules or ions of gas, liquid, or solute from an area of greater concentration to an area of lighter concentration.

All living cells of root, stem and leaves respire all through day and night. In higher plants, the respiration takes place through stomata present on leaves. The older stems exhibit the gaseous exchange through lenticels present on the bark. In lenticels the cells are loose and thin walled and have many air spaces in them. They are often projected above the outer covering of stem.

Opening and Closing of Stomata

Stomata are the minute pores found on the epidermis of leaves. These help in the exchange of gases during the time of photosynthesis and respiration. It also helps in transpiration; this kind of transpiration that takes place with the help of stomata is called stomatal transpiration.

Structure of stomata

In the stoma two guard cells bound a minute elliptical pore.

Guard cell : characters

1.      These guard cells are basically modified epidermal cells which are in shape of kidney beans.

2.       The wall of guard cells near the pore is thick but the outer wall is thin, elastic and semi-permeable.

3.      Guard cells are filled with chloroplast

4.      Sometimes the immediate cells surrounding the guard differ from epidermal cell and they are called subsidiary or accessory cells.

5.      In monocots the guard cells are dumb-bell in shape.

Mechanism of opening and closing of stomata

Opening and closing of stomata occur due to turgor change in guard cells.

Opening of guard cells

Due to endosmosis   -------------à increase in turgor of guard cells    -----------------à causes stretching and bulging of outer thin walls  --------------à results in pulling apart of inner thicker wall ---------à this creates an opening or pore in the guard cells of stomata

Due to endosmosis the turgor pressure of guard cells increases which leads to stretching and bulging of outer thin walls. When the outer thin wall swell, it stretches out and in turn pulls the inner thick wall. This pulling back of iner wall creates a pore between the guard cells.

Closing of guard cells

Turgor pressure of guard cells decreases due to exosmosis    ------------à inner wall of guard cell sags     -----------à the pore created closes.

When the turgor pressure of guard cells decreases due to exosmosis the inner wall of guard cells drop back in its position thus closing the pore.

What causes endosmosis and exosmosis?

During day the starch of guard cells is converted into sugar. This sugar increases the osmotic content of guard cells which lead to endosmosis and finally opens the stomata.

During night, the sugar is converted back to starch reversing the whole process and thus closing the stomata.

hetertotrophic nutrition

Heterotrophic nutrition

Heterotrophic (Gk. Hetero=different; trophe= nourishment) nutrition: this kind of nutrition is followed by all animals , fungi, some prosists, bacteria and nn green plants. These organisms obtain their food from other plants and animals beacuse they have no chlorophyll to trap solar energy and make their own food. Animals showing heterotrophic nutrition are called heterotrophs.

On the basis of nature of food heterotrophic nutrion is of three types:

1.     saprophytic nutrition

2.     parasitic nutrition

3.     holozoic nutrition

saprophytic nutrition is the mode of nutrition in which heterotrophs get their food from dead and decaying organisms

Saprophytic organisms produce digestive enzyme, these enzyme when released on the food material they breaks down to soluble food . this food in soluble form is absorbed. This method leads to the decay and decomposition of organic food material.

 Saprophytes are mainly bacteria and fungi. Yeast, mushrooms and moulds are saprophytic fungi.yeast feed on sugar solution which helps in its growth. Neottia and monotropa are flowering plants which are saprophyte.

Parasitic mode of nutrition is the phenomenon in which an organism(parasite) lives in or on the body of another organism(host). Parasite absorb the food from the body of their host, in thos process they make damage or even kill their host organism. This phenomenom is called parasitism. This mode of nutrition is showed by non-chlorophyllous plant, viruses and some fungi.

In fungi, mycelium go deep in the host tissue and secrete enzyme. The soli food in host body is converted in soluble form and then absorbed abd assimilated by fungal hyphae. For this purpose, tips of hyphae gets rounded and are called haustoria. Some parasitic bacteria cause diseases in plants and animals, these are pathogens.

Total stem parasite: cuscuta

Partial stem parasite: viscum, loranthus

e.g., puccinia (wheat and barberry plant), roundworms,

ectoparasite e.g., bedbug, head louse,

endoparasite e.g., trypanosome, malarial parasite(intracellular parasite)

taenia, ascaris (coelozoic parasite)or blood fluke, filarial worm (histozoic in body tissue)

green species of euglena, e.g., E.viridis, E.gracilis (autotrophic in light but saprophytic in dark). This dual mode is called myxotrophic nutrition.

Holozoic nutrition is the mode in which digestion is always inside the body, either intercellularly or intracellularly.  Organisms can feed on solid food material. The food may be whole plant animal or their part

Photosynthesis : mechanism

Photosynthesis : mechanism

The process of photosynthesis is divided in two phases:

Dark phase (photochemical reaction)

Light phase (chemical reaction)

Light phase: this reaction phase require light therefore also called photochemical reaction.

First the light energy is absorbed by chlorophyll. This takes place in the grana region. The chlorophyll a pigment traps the visible light in form of quanta or photons (energy). When the chlorophyll molecules are exposed to light they gets exited and emits electrons. Photons are the energy packets emitted by light. This energy is inversely proportional to its wavelength, shorter the wavelength of light higher is the energy of photon.

Light energy is converted into chemical energy and splits water molecule into hydrogen and oxygen. emitted electrons are channelled through electron transport chain in chloroplast. The photons absorbed by chlorophyll  then carries out three function:

i.                    Formation of ATP (Adenosine triphosphate) . ATP is the source of energy used during the during the dark phase of photosynthesis. ATP is formed when ADP (Adenosine diphosphate)  joins a phosphate group.

ADT + Phosphate Gr ----------à ATP

ii.                  Photolysis of water. Decomposition of water with the help of light energy  into hydrogen and oxygen is called photolysis of water

Water + energy -------à Hydrogen + oxygen

This oxygen is by product of photo synthesis.

iii.                Synthesis of NADPH (reduced nicotinamide adenine dinucleotide phosphate). Hydrogen ions released from water  joins with NADP and reduces it to NAPH. This is also used in dark reaction.

Dark phase: this is the light independent phase. It does not need light energy and thus it is completely chemical process. This reaction takes place in stroma region of chloroplast

Carbon-dioxide is reduced to carbohydrate. Carbon dioxide is reduced to glucose by hydrogen in NADPH and energy in ATP. This reaction is also called clavin cycle. Melvin clavin explained this process using radioactive carbon.

ATP and NADPH molecules together are called as assimilatory power.

RuBP  + CO₂  + NADPH  + ATP  ------à   RuBP  +  C₆H₁₂O₆    +  ADP  +  NADP  + Po₄

RuBP : ribulose biphosphate enzyme

RuBP combines with  CO₂ to make carbohydrate and regenerating RuBP.

Diagrammatic representation of photosynthesis mechanism.

  

Significance of photosynthesis

1.     Food . food is synthesized from raw material like carbon-dioxide and water.

2.     Oxygen . oxygen required for respiration and combustion processes are formed as a  by-product of photosynthesis.

3.     Fuels. Fossil fuel lie coal, oil natural gas are forms of stored solar energy synthesized by photosynthesis.

PHOTO-AUTOTROPHIC MODE OF NUTRITION

PHOTO-AUTOTROPHIC MODE OF NUTRITION

Photo-autotropic mode of nutrition or photosynthesis  is the process by which photoautotrophs synthesize food in the presence of sunlight, CO₂ and H₂O. by this method solar energy is trapped by autotrophic organism and converted into food. In this process carbohydrates are synthesized from simple inorganic compounds like carbon dioxide and water in presence of chlorophyll and sunlight.

In plants the unused carbohydrates are stored in form of starch.

In animals unused food is stored in form of glycogen.

Chloroplast

Chloroplasts(G.k  chloros- grass green   plastos-moulded) are the green plastids which help in the synthesis of organic food. These are uniformly distributed in cytoplasm of plant cell.  Chloroplast is found in the upper surface of leaf, thus exposing it to maximum sunlight so that more solar enery is absorbed.

It is covered by a double membranous structure called chloroplast envelope where each membranous structure is a unit of plasma membrane like structure. This membrane can be observed by electron microscope.

Protein matrix present in chloroplast is called matrix or stroma.

Lamellae or thylakoids are a membrane system which run parallel to each other in stroma. There are two types of thyllakoids present in higher plants. Large thylakoid (stroma thylakoid)  extend from one end to other end of chloroplast , small thylakoid (grana thylakoid) are disk shaped and closely placed to each other to form grana. Grana and stroma thylakoid fuse with each other in the region of granum

Photosynthetic pigments

These are the pigments involved in photosynthesis. e.g.  chlorophyll, carotenoid (carotenes and xanthophylls) , anthocyanin, phycobilins (phycocyanin and phycoerythrin)

Chlorophylls are green pigment present in chloroplast and gives green color to plants. These are of seven types . chlorophyll a, b, c, d, e, bacteriochlorophyll and bacterioviridin. These traps solar energy and converts it into chemical energy during photosynthesis.

Carotenoids are lipid and are classified in two groups: carotenes which are orange red in color. Xanthophylls are yellow in color.

Carotenoid absorb light energy and transfer it to chlorophyll a and act as accessory pigment.

Site of photosynthesis

Photosynthesis takes place in chloroplast which contain the pigment chlorophyll. These pigments are therefore available in the green part of plants like leaves , green stem.

Carbon dioxide diffuses in the leaf through stomata present in lower surface of leaf. Chloroplast which is present in the upper surface of leaf captures more sunlight.  Leaf vein brings the water .

Raw material needed during phtotosynthesis

1.     Carbon dioxide – forms 0.32 % of total atmosphere. Provides carbon for carbohydrate formation. Hydrophytic plant use CO₂ dissolved in water

2.     Water – provides hydrogen for carbohydrate foemation. Helps in keeping stomata pores open. Deficiency of water  can cause closing of stomata thus checking CO₂  to enter the leaf.

Solar Energy is trapped in chloroplast and converted into chemical energy. This chemical energy is ATP ( adenosine triphosphate).

Carbohydrate synthesis during photosynthesis

6CO₂ + 6H₂O   ---^{light+chlorophyll}----à C₆H₁₂O₆ + 6O₂

Photosynthesis is the process where light energy is converted in chemical energy. Solar energy is captured by chlorophyll in presence of carbon-dioxide and oxygen and carbohydrate (food) and oxygen are formed. this biochemical  activity of plant uses solar energy to make their food, this carbohydrate undergoes respiration to release energy to be used in various metabolic activities.

Contd…

nutrition

                                                                                                            Previous topic: Life process intro

Nutrition is the process of intake of food,its digestion, absorption and distribution to diffrent part of body

Food an organic substance, is used by living beings to remain alive. It is the source of energy and provide raw material for the synthesis of body constituents. When consumed, food passes through biochemical changes and finally the nutrients are absorbed by or body. The main classification of types of food:

Carbohydrate and fat (energy giving)

Protein and mineral salt (body building)

Vitamin and mineral (regulating food)

The simplest form of food is glucose, this does not need and any further breakdown and when consumed gives instant energy.

Mode of nutrition (on the basis of taking of food)

1.       Autotrophic nutrition

2.       Heterotrophic nutrition

Autotrophic nutrition (Gk. Auto-self, troph-nutrition) they use raw material from environment to manufacture their own food. Autotrophs are divided in two category on the basis of the way they manufacture their food

a.       Photo-autotrophic (photosynthesis)

b.      Chemo-autotrophic(chemosynthesis)

A.      photosynthesis is shown by green plants, protists and photosynthetic bacteria. These contain chlorophyll, a green pigment which help them sysnthesize food in presence of simple raw material like CO₂, H₂O in presence of sunlight.

B.      In chemosynthesis energy stored in food is obtained from some chemical, they require only organic material from atmosphere, carbon is obtained from CO₂._.  e.g.; Hydrogen  bacteria, iron bacteria, nitrifying bacteria.
 
    Next topic: Photo autotrophic mode of nutrition

Life processes an intoduction

What are life processes? 

The basic functions performed by living beings to sustain their life. living being exhibit many activities
1. nutrition
2. respiration
3. transport of material
4.blood circulation
5. excretion
6.reproduction

 Although most activities are common in both plants and animals  some of the mentioned activities are shown by exclusively in plants.

for living being to sustain their life energy is required, which is obtained by food. The energy from food is processed inside our body to produce energy,  thus the need of nutrition  arises, For the various functioning of body, for breaking down of molecule and performing oxidation and reduction reactions. This reaction requires oxygen from outside the body which is fulfilled by respiration- also known as aerobic catabolism for its tissue breakdown process.

The nutrients obtained by food are required to be transferred to the whole body for which an effective transport system is required. Blood circulation also helps in transport of oxygen and nutrients. During all these process wastes and toxins are produced in our body which had to be flushed out, this process of expelling out wastes is called excretion. For maintaining a certain species reproduction is equally important.

the branch of science which is deals with the various life processes and the related organs of body is known as physiology.

Next topic: Nutrition