Biology-Life_Processs_ NUTRITION

Revision_purposes

Life Processes

The basic and essential activities performed by a living organism to sustain and maintain life.

Nutrition

The process by which a living organism obtains and utilizes food is called ‘nutrition’.

Autotrophic nutrition

mode of nutrition in which organisms prepare their own food using simple inorganic substances like CO₂ and H₂O. Eg : green plants, algae, blue green algae

Heterotrophic nutrition

mode of nutrition where an organism depends on another for food and nutrients. Eg : humans, animals, etc.

Types of Autotrophic nutrition

1. Chemosynthesis - make own food but with chemicals. purple sulfur bacteria.

2. Photosynthesis - green plants, cyanobacteria, algae, bacteria

Types of Heterotrophic nutrition

1. Holozoic - animals that take in solid food which is then broken down inside the body. eg : animals, amoeba

2. Parasite : live inside/outside another organism (host) and derive nutrition from it. eg : cuscutta, ticks, leech

3. Saprophytes : organisms that feed on dead and decaying matter. eg : fungi, mushroom

Photosynthesis formula (Reactants - products)

6CO₂ + 12H₂O (chlorophyll, sunlight) —> C₆H₁₂O₆ + 6O₂ + 6H₂O

Main events of photosyntesis (Very Important!!)

1. Absorption of light energy by chlorophyll

2. Conversion of light energy into chemical energy to split water molecules into hydrogen and oxygen

3. Reduction of CO₂ to carbohydrates (/glucose/energy)

Plants store glucose in the form _______ and humans in the form of ______.

plants : starch ; humans : glycogen

Label the following diagram of stomata

A : guard cells

B : stomatal pore

C : chloroplast

Functions of stomata (NTN)

1. exchange of gases

2. transpiration

Photosynthesis in desert plants

1. stomata opens at night to take in CO₂ (to reduce water loss)

2. stomata closed during day

3. CO₂ taken at night used for photosynthesis

Nutrition in Amoeba (mid question)

1. Ingestion - surrounding food particle with pseudopodia forming food vacuole.

2. Digestion - enzymes secreted into food vacuole to break it into simpler soluble substances

3. Absorption - digested food absorbed and used as energy

4. Assimilation - absorbed nutrients utilized in life processes.

5. Egestion - undigested food expelled out.

Nutrition in paramoecium.

• Follows holozoic nutrition.

• ingestion : using cilia.

• rest like amoeba

Label the following diagram (Human Alimentary Canal)

A : Tongue

B : Mouth (Buccal Cavity)

C : Oesophagus

D : Diaphragm

E : Stomach

F : Gall bladder

G : Bile duct

H : Liver

I : Pancreas

J : Small intestine

K : Large intestine

L : Appendix

M : An^s

Teeth

• crushes food ; forms uniform texture

• salivary glands secrete saliva

• contains enzymes salivary amylase which breaks down complex sugars (Starch) into simple sugars (maltose)

Oesophagus

• food pipe

• connects mouth to stomach

• peristalsis - rhythmic contractions in the alimentary canal to push the food down.

Stomach

Secretes gastric juice containing :

• HCL - creates acidic medium (helps pepsin, kills germs)

• Pepsin - digests proteins

• Mucus - protects stomach inner lining from HCL

Food stays in stomach for 3-4 days

Small Intestine

1. Longest part - 7m

2. Coiled.

3. Site of digestion and absorption

4. Recieves secretions from :

• Liver (Bile juice) - makes food alkaline and emulsifies fats

• Pancreas (pancreatic juice) - trypsin (proteins) ; lipase (fats) ; pancreatic amylase

• Intestinal glands - secretes intestinal juice

(Stomach part-2) Breaking down of compunds

Proteins —> amino acids

Carbohydrates —> glucose

Fats —> fatty acids + glycerol

(Stomach part-3) Absorption in stomach

• Villi (projections) in the inner wall

• increases surface area

• rich blood supply transports absorbed nutrients to all body cells.

• nutrients used for energy, growth and repair of tissues.

Large Intestine

• absorbs water from undigested food

• prepares waste

An^s

Egestion - removal of undigested waste

Controlled by anal sphincter