LIFE PROCESSES IN LIVING ORGANISMS PART 1

LIFE PROCESSES IN LIVING ORGANISMS PART 1

1. How are the food stuffs and their nutrient contents useful for body?

• The food stuffs are digested and converted into soluble nutrients.
• Carbohydrates & fats provide energy
• Proteins are the structural components of cells
• Vitamins & Minerals perform function of Protection and regulation.
• The nutrients are carried by blood to every cell of the body.
• Oxygen inhaled at the time of respiration is also carried to every cell.
• This oxygen is carries out oxidation of nutrients and thus energy is produced.
• This energy helps the body to carry out all its functions.
• Thus, they help in the growth of body.

2. What is the importance of balanced diet for body?

• A balanced diet has carbohydrates, proteins, fats, vitamins and minerals in the right proportion.
• It helps in proper growth of the body.
• It increases capacity of work by providing energy.
• Increases immunity.
• It is essential for good health.

3. Which different functions are performed by muscles in body?

Muscles are responsible for movements in the body.

There are three types of muscles –

1. Striated muscles – Attached to bones and bring about movements of legs and hands.
2. Non striated muscles – Bring about movements of involuntary organs.
3. Cardiac muscles – Bring about contraction and relaxation of heart.

4. What is the importance of digestive juices in digestive system?

• The digestive juices contain various enzymes that help in digestion of food.
• The enzymes act as catalysts for digestion process.
• They convert complex food into simpler form.
• They convert proteins to amino acids, carbohydrates to glucose and lipids to fatty acids.

5. Which system is in action for removal of waste materials produced in human body?

Waste materials in human body are removed by the excretory system.

6. What is the role of circulatory system in energy production?

It transports glucose from digestive system and oxygen from respiratory system to every cell. Thus, they help in energy production.

7. How are the various processes occurring in human body controlled? In how many ways?

• The nervous system and the endocrine system bring about control by nervous and chemical coordination in the body.
• Nervous control is brought about with the help of brain, spinal cord and nerves.
• Chemical control is brought about with the help of chemical substances called hormones.

LIVING ORGANISMS AND LIFE PROCESSES –

• In our body, various systems work in coordination with each other.
• For their functioning, they need energy.
• Carbohydrates, fats and lipids are the main sources of this energy.
• Mitochondria synthesize energy by using these nutrients.
• Oxygen is necessary for this process
• Plants – They are autotrophic and synthesize their food by photosynthesis. They utilize some energy for their body processes and remaining energy is stored in fruits, roots, stems, leaves, etc.
• Animals – They consume plants and obtain nutrients.

Use your brain power (page 12) –

Why players consume foods during breaks of the game?

• They generally eat protein rich food or carbohydrates (like banana)
• They are quick source of energy
• They also drink water, glucose and electrolyte to stay hydrated

Can you recall (Page 12) –

What is respiration? How it occurs?

• It involves release of energy by oxidation of food
• It involves taking in oxygen- rich air and giving out air containing CO2
• Oxygen is used for cellular respiration to release energy

Can you tell? (Page 13) –

1. How many atoms of C, H and O are respectively present in a molecule of glucose?

One molecule of Glucose contains 6 atoms of Carbon, 12 atoms of Hydrogen, 6 atoms of Oxygen (Formula – C₆H₁₂O₆)

2. Which types of chemical bonds are present between all these atoms?

The type of bond present between these atoms is covalent bond.

3. In terms of Chemistry what happens actually when a molecule is oxidized?

When a molecule is oxidized, it accepts oxygen or loses Hydrogen. It also loses electron and gains a positive charge.

Living Organisms and Energy Production

2 levels of respiration –

1. Body level – Exchange of CO2 and O2 between body and environment.
2. cellular level: –

• Occurs in mitochondria.
• Oxidation of food stuffs inside the cells.
• Carbohydrates are used for energy production in the form of ATP.
• Step by step oxidation of glucose is done during cellular respiration.
• Two methods of cellular respiration – Aerobic and anaerobic.

1. Aerobic Respiration –

• Process of energy production in presence of oxygen.
• Three steps – Glycolysis, Tricarboxylic acid cycle, Electron transfer chain reaction.

1. Glycolysis –

• First step of Aerobic / Anaerobic respiration.
• Also known as EMP Pathway as it was discovered by scientists – Gustav Embden, Otto Meyerhof, Jacob Parnas
• Occurs in the cytoplasm.
• Glucose is oxidized in stepwise manner.
• 1 Glucose molecule à 2 Pyruvic acid molecules.(C3H4O3)
• ATP – 2, NADH – 2, water – 2
• Glucose à Pyruvic acid à Acetyl CoA
• NADH – 2, CO2 – 2
• Acetyl CoA enters mitochondria.

2. Kreb’s Cycle –

• Second step of aerobic respiration
• Discovered by Sir Hans Krebs
• Occurs in Mitochondria
• Acetyl CoA enter the Mitochondria
• Acetyl part is completely oxidized through this process
• Acetyl part =citric acid (C6H8O7)
• Byproducts – CO2, H2O, NADH-3, FADH2-1, ATP-1
• CoA is recycled to convert pyruvic acid to Acetyl CoA
• Citric acid is formed as byproduct – Citric acid Cycle
• Citric acid contains 3 Carboxylic acid molecules – Tricarboxylic acid cycle

3. Electron transfer chain reaction:

• Occurs in mitochondria.
• Molecules of NADH2 and FADH2 participate in the chain reaction and their oxidation (removal of hydrogen) takes place.
• The removed hydrogen reacts with oxygen to form water molecule
• During this process, synthesis of ATP takes place with the help of energy release.
• 1 NADH – 3 ATP molecules
• 1 FADH2 – 2 ATP molecules
• Thus 1 glucose molecule gives CO2 and H2O along with energy after complete oxidation.

Total energy –

1. In glycolysis: 2ATP + 2NADH2 x 3=6ATP 8 ATP in glycolysis
2. In Krebs cycle:

NADH2 3 + 3 (as 2 molecules of acetyl are oxidized) = 6 x 3 = 18 ATP

FADH2 1+1 = 2 x 2 = 4 ATP

ATP 1+1=2 ATP

24 ATP in Krebs cycle

3. Intermediate step (pyruvic acid àacetyl CoA)

2NADH x 3 = 6 ATP

     TOTAL = 38 ATP

ATP: Energy rich molecule:

• ATP (Adenosine Tri Phosphate) is energy rich molecule
• Energy is stored in bonds by which phosphate groups are attached to each other.
• These molecules are stored in cell and used as per need by breaking the phosphate bonds.
• Whenever the cell needs energy, ATP hydrolyzed (Process of breaking bonds – Hydrolyze) to produce ADP and energy is released.
• On hydrolysis of an ATP molecule, 7.3 Kcal energy is released.
• As energy is obtained by breaking the bonds, ATP is called energy currency of the cell.
• There are 3 components of ATP –

1. Nitrogenous base(adenine)
2. Pentose sugar – Ribose (C₅H₁₀O₅)
3. Three phosphate groups

• When carbohydrates are insufficient (during fasting), lipids and proteins are utilized for energy production.
• Lipids are converted to fatty acids; proteins are converted to amino acids. Both are converted to Acetyl Co-A for energy production.
• It undergoes complete oxidation and release energy.

1. Anaerobic respiration:

• The oxidation of glucose in absence of oxygen is called as anaerobic respiration.
• It occurs in some microbes like bacteria, yeast and lower organisms perform anaerobic respiration. Also, human muscle cells perform anaerobic respiration during vigorous muscle activities.
• It occurs in 2 steps – glycolysis and fermentation.
• Glucose is incompletely oxidized to release energy.
• Pyruvic acid produced is converted into other organic acids or alcohol (C2H5OH) it is called fermentation.
• It occurs in presence of certain enzymes like Zymase
• In oxygen deficiency, some plants and animals also perform anaerobic respiration.
• Seed respires anaerobically if soil is submerged in water.
• Muscle cells respire anaerobically during exercise. When we perform rigorous exercise, the muscle cells require more energy but when less energy is supplied, the cells perform anaerobic respiration and produce lactic acid. As a result, we get cramps in our muscles due to accumulation of lactic acid. During rest, the lactic acid is reconverted to pyruvic acid and the cells perform aerobic respiration again.

Energy from different food components:

1. Carbohydrates:

• Sources: Cereals
• They are converted to glucose after digestion.
• Glucose is broken down by glycolysis and energy is produced.
• We get 4 Kcal energy from 1 g Carbohydrates
• Excess carbohydrates are stored in liver and muscle cells in form of glycogen

2. Proteins:

• Sources:

Animal sources: first class proteins

Plant sources

• These are the macromolecules formed by amino acids which are connected by peptide bonds.
• When proteins are digested, amino acids are formed which are absorbed and transported to each cell via blood. From the amino acids various proteins are made according to function of cell.
• Storage –

Excess amino acids are broken down into ammonia and eliminated out of the body.

Sometimes, excess proteins are converted into glucose through gluconeogenesis.

Gluconeogenesis

Proteins                                               Glucose

• Plants produce amino acids from minerals like denovo.
• RUBISCO is an abundant protein present in chloroplast of plant.
• We get 4 Kcal energy from 1 g proteins

1. Fats / Lipids:

• Sources: milk products,
• Formed by specific bonds between fay acids and alcohol. Their digestion forms fatty acids and alcohol.
• Fatty acids are used for following processes-
  • Phospholipids (essential for formation of plasma membrane) production.
  • Production of hormones like progesterone, oestrogen, testosterone, aldosterone, etc
• Excess lipids are stored in adipose tissue.
• We get 9 Kcal energy from 1 g fats

 

2. Vitamins:

• Group of heterogenous compounds necessary proper functioning of body.
• Six main types – A, B, C, D, E and K
• Fat soluble- A, D, E, K
• Water soluble – B, C
• Vit B2(riboflavin) – for production of FADH2
• Vit B5(nicotinamide) – for production of NADH.

3. Water:

• Body contains about 65 – 70 % water.
• 70% water is present by weight in cell.
• Blood plasma contains 90% water.
• Water loss disturbs body functioning.

4. Fibres:

• Sources: leafy vegetables, fruits, cereals
• They can’t be digested but help in digestion of other substances and removal of wastes.

Can you recall? (Textbook page no. 16)

From where do we obtain lipids?

Lipids are obtained from foodstuffs like oil, ghee, butter, nuts, fish, meat, etc.

Think (Textbook page no. 17)

Many times, you cannot eat hot food due to inflammation/ulceration in mouth.

• Ulcer is caused due to reasons like tissue injury by accidental biting of cheek, stress, deficiency of vitamin B2, zinc, folic acid or iron.
• Eating hot or spicy food during inflammation/ulceration in mouth can irritate the injured cells/tissue.
• Therefore, many times, we cannot eat hot food due to inflammation or ulceration in mouth.

 

Some persons experience difficulty in night vision since childhood or adolescence.

• Inability to see in dim light in known as night blindness.
• It is caused due to deficiency of vitamin A in the diet.
• Therefore, some persons experience difficulty in night vision since childhood or adolescence.

Use your brain power. (Textbook page no. 17)

Many times, we experience dryness in mouth.

It is caused due to dehydration.

While running, walking, playing or other activities, our body loses water in the form of sweat.

Thus, to maintain the water level in the body we feel thirsty or experience dryness in the mouth.

Oral rehydration solution (Salt-sugar-water) is frequently given to persons experiencing loose motions.

• In loose motions/ diarrhea, body loses excess fluids and salts.
• This causes dehydration which can be dangerous.
• In such cases the body can be rehydrated by giving a solution containing salt and sugar (For e.g., ORS Oral Rehydration Salts).
• Drinking this solution helps to replace the fluids and essential salts lost due to diarrhoea.
• Therefore, oral rehydration solution (Salt sugar-water) is frequently given to persons experiencing loose motions.

We sweat during summer and heavy exercise.

• During summer and heavy exercise, our body temperature rises.
• Our body maintains its temperature by sweating.
• The sweat in turn evaporates and keeps our body cool.

Collect information

1. What are symptoms of diseases like night blindness, rickets, beriberi, neuritis, pellagra, anemia, scurvy?

Disease	Symptoms
Night blindness	Inability to see in low light
Rickets	Softening of bones leading to fractures
Beriberi	Pain in limbs, shortness of breathing, swollen feet
Neuritis	Loss of sensation
Pellagra	High sensitivity to sunlight causing sores
Anemia	Dizziness, Fatigue, weakness
Scurvy	Bleeding of gums

 

2. What do you mean by coenzymes?

These are small, nonprotein molecules. Coenzymes hold an atom or group of atoms, allowing an enzyme to work and catalyze reactions

Example – B vitamins

3. Find the full forms of FAD, FMN, NAD, NADP.

FAD – Flavin Adenine Dinucleotide

FMN – Flavin mononucleotide

NAD – Nicotinamide Adenine Dinucleotide

NADP – Nicotinamide Adenine Dinucleotide Phosphate

4. How much quantity of each vitamin is required every day?

 

Vitamin	Quantity
A	5000 IU
B1(Thiamine)	1.5 mg
B2 (Riboflavin)	1.7 mg
B3 (Niacin)	20 mg
B5 (Pantothenic acid)	10 mg
B6	2 mg
B7 (Biotin)	300 micrograms
B9 (Folic acid)	400 micrograms
B12	6 micrograms
C	60 mg
D	400 IU
E	30 IU
K	80 micrograms

 

Can you tell (Page 17)

1. What happens to the cells of injured tissue?

The cells in that particular tissue get damaged. Sometimes the cells become dead if the injury is severe. In such cases, the cells lose their ability of self-repair.

2. Whether new cells are formed during healing of wound?

Yes.

3. Do the plants get injured when do we pluck the flowers? How are those wounds healed?

Yes, the cells get injured. To heal the injury, the meristematic tissue give rise to new cells at the site of injury.

4. How does the growth of any living organism occur?

Growth of living organism occur by cell division.

5. Does the number of cells in their body increase? If yes, how?

Yes, the number of cells in the organism’s body increases. The number of cells increases by mitosis.

6. How the new individual of a species is formed from existing one of same species?

By the process of reproduction

CELL DIVISION –

It is the property of cells of living organisms due to which a new organism is formed from existing one.

Two main types – mitosis and meiosis.

Importance of cell division –

It helps in –

• Renewing of damaged cells.
• Production of new cells from older ones.
• Maintains the total number of chromosomes.
• Also helps in the survival and growth of living organisms.
• Wound healing, blood cell formation
• Smoothly running various life process

1. MITOSIS –

• This is a type of cell division in which a cell divides to form two identical daughter cells which are identical to the parent cell.
• It is completed in two steps – karyokinesis and cytokinesis.
• Karyokinesis is nuclear division which is sub-divided into prophase, metaphase, anaphase, and telophase
• Cytokinesis is division of cytoplasm.

    A) Karyokinesis:

Completed in 4 steps:

1. Prophase:

• Thread like chromosomes (Chromatin fibres) begin to condense.
• Chromosomes become short and thick
• Formation of sister chromatids.
• Centrioles duplicate and move to opposite poles.
• Nuclear membrane and nucleolus start to disappear.

b ) Metaphase:

• Nuclear membrane completely disappears.
• Chromosomal condensation completes.
• Chromosomes are clearly visible along with sister chromatids.
• Chromosomes are arranged parallel to equatorial plane of cell.
• Spindle fibres are formed between centromere and both centrioles.

c) Anaphase:

• The shortest phase.
• Centromeres split and sister chromatids are pulled apart with the help of spindle fibres at opposite ends.
• Each set of chromosomes reach at 2 opposite ends.
• Chromosomes appear like bunch of bananas.

d) Telophase:

• It is reverse of prophase
• Daughter chromosomes begin to decondense. Chromosomes become thread like and start disappearing.
• Spindle fibres completely disappear.
• Two daughter nuclei formed.
• Reappearance of nuclear membrane and nucleolus.

      Cytokinesis:

• After karyokinesis, cytoplasm divides and 2 daughter cells are formed.
• In plant cell, cell plate is formed then cytokinesis occurs.
• In animal cell, a notch is developed which gradually deepens and 2 daughter cells are formed.

Significance of mitosis:

• Essential for growth
• Necessary for restoration of emaciated(ill)body
• Healing wound
• Formation of blood cells
• The chromosome number is maintained constant.
• The hereditary material (DNA) is also equally distributed.
• It ensures equal distribution of the nuclear and the cytoplasmic content

MEIOSIS

It leads to formation of male and female gametes i.e., egg and sperm cells. Takes place in two steps – Meiosis I and Meiosis II

1. MEIOSIS I

It is again subdivided into prophase I, metaphase I, anaphase I, telophase I

1. Prophase I:

It is longer and complex. It is subdivided into 5 phases.

1. Leptotene: Chromosomes become visible and start to condense. Formation of homologous chromosomes.
2. Zygotene: Pairing of homologous chromosomes (Synapsis) and formation of bivalents (Pair of homologous chromosomes – Bivalents)

• Pachytene: Crossing over (exchange of genetic material) takes place in non-sister chromatids of homologous chromosomes.

1. Diplotene: Bivalents separate from each other except the site of crossing over. (They look like X shaped structure. The point of attachment is called chiasmata.)
2. Diakinesis: Spindle fibres are originated, and chromosomes start to separate.

                     Nucleolus and nuclear membrane disappear

1. Metaphase I

• The bivalents become arranged around the equator of the spindle, attached by their centromeres

2. Anaphase I:

Centromeres split and sister chromatids are pulled apart with the help of spindle fibres at opposite ends.

Each set of chromosomes reach at 2 opposite ends.

3. Telophase I:

• Chromosomes become thread like and start disappearing.
• Spindle fibres completely disappear.
• Two daughter nuclei are formed.
• Reappearance of nuclear membrane and nucleolus.

B) MEIOSIS II:

It is similar to mitosis.

The 2 haploid cells formed in meiosis I undergo further division and forms 4 haploid cells.

It is also having 4 stages which are similar to mitosis. i.e., prophase II, metaphase II, anaphase II and telophase II

      a) Prophase II

• Nucleoli & nuclear envelops disappear
• Chromatids become short and thick
• Centrioles move at opposite poles
• Spindle fibers appear

     b) Metaphase II

• Chromosomes get arranged along the equatorial plate

        C) Anaphase II

• Centromeres divide and the spindle fibers pull the Chromatids to opposite poles

       D) Telophase II

• Four haploid daughter cells are formed
• Chromosomes are uncoiled, become indistinct
• Spindle fibers disappear

 Use your brain power (Page 20)

1. What do you mean by diploid (2n) cell?

The cell having two sets of chromosomes.

2. What do you mean by haploid (n) cell?

The cell having one set of chromosomes.

3. What do you mean be homologous chromosomes?

The morphologically and structurally similar chromosomes present in a diploid cell.

4. Whether the gametes are diploid or haploid? Why?

The gametes are haploid because they are formed by meiotic division of germ cells

5. How are the haploid cells formed?

Haploid cells are formed due to meiotic division of a diploid cell.

6. What is the importance of haploid cells?

The haploid cells (gametes) are required for sexual reproduction.

They unite at the time of fertilization.

The fusion of gametes leads to genetic recombination which is important for evolution.

 

 

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