Q1.What is nutrition? What are the five stages of nutrition

Answer. Nutrition is the process by which organisms obtain and utilize food for growth and energy. There are two main types: 

1. Autotrophic Nutrition 

   Organisms make their own food using sunlight (photosynthesis) or chemicals (chemosynthesis). Examples: 

   – Green plants (use chlorophyll) 

   – Some bacteria (near volcanic vents) 

   They convert inorganic matter (CO₂, water) into organic compounds (glucose).

2. Heterotrophic Nutrition 

   Organisms depend on other organisms for food. Subtypes: 

   – Holozoic (humans, animals – ingest solid food) 

   – Saprophytic (fungi – absorb nutrients from dead matter) 

   – Parasitic (ticks, tapeworms – steal nutrients from hosts)

3. Holozoic Nutrition 

   Complex food is ingested, digested, and absorbed. Steps: 

   – Ingestion (eating) → Digestion (breaking down) → Absorption → Egestion (waste removal) 

   Examples: Humans, lions, birds.

4. Saprophytic Nutrition 

   Organisms feed on dead/decaying matter. They secrete enzymes to digest externally, then absorb nutrients. 

   Examples: 

   – Mushrooms 

   – Bread mold 

   cleans the environment.

5. Parasitic Nutrition 

   One organism (parasite) harms another (host) while taking nutrients. Types: 

   – Ectoparasites (live outside host, e.g., lice) 

   – Endoparasites (live inside host, e.g., tapeworms) 

   Often cause diseases in hosts.

6. Symbiotic Nutrition 

   Two organisms live together and mutually benefit. Example: 

   – Lichens (algae and fungus) 

   – Rhizobium bacteria in legume roots.

Q2. Write a short note on the Ingestion of food in different Animals 

Answer.  Different animals have specialized feeding mechanisms: 

– Humans use teeth to chew food 

– Amoebas extend pseudopodia to engulf food 

– Birds swallow food whole using beaks 

– Butterflies suck nectar through proboscis 

– Snakes can swallow prey larger than their heads 

These adaptations help animals consume food efficiently in their environments.

Q3. With the help of a diagram, describe nutrition in an Amoeba.

Q4. Describe the different types of teeth in human jaw 

Answer. Adult humans have four types of teeth: 

– 8 incisors for cutting food 

– 4 canines for tearing 

– 8 premolars for crushing 

– 12 molars for grinding 

This arrangement (total 32 teeth) allows efficient mechanical breakdown of different food types during chewing.

Q5. What are Digestive Glands? Name the digestive glands present in the human digestive system, along with their secretions

Key digestive glands include: 

– Salivary glands (produce saliva with digestive enzymes) 

– Liver (produces bile for fat digestion) 

– Pancreas (secretes digestive enzymes into small intestine) 

These glands release substances that chemically break down food into absorbable nutrients.

Q6. Describe the process of digestion in human beings. Mention the organ involved in it.

Answer. The digestive system: 

– Breaks down complex food molecules 

– Absorbs nutrients into the bloodstream 

– Eliminates undigested waste 

– Includes alimentary canal (mouth to anus) and accessory organs like liver and pancreas that help in digestion.

Q7. What part of the digestive system does absorption take place in?

Answer. Digested nutrients enter blood circulation: 

– Carbohydrates become glucose 

– Proteins become amino acids 

– Fats become fatty acids 

Cells use these with oxygen in cellular respiration to produce ATP (energy currency) for all body functions.

Q8. What does the liver secrete? How does it help in digestion?

Answer. The liver’s key digestive secretion is bile, which performs the vital function of fat digestion. Through a process called emulsification, bile breaks apart large fat molecules into smaller droplets.

This action significantly increases the surface area of fats, allowing digestive enzymes like lipase to work much more effectively. By transforming fats into this more accessible form, bile enables proper digestion and absorption of dietary fats and fat-soluble vitamins in the small intestine.

This emulsification process is essential for our body to properly utilize the fats we consume in our diet.

Q9. How do we get energy from the nutrients that are digested and absorbed?

Answer. Digested nutrients (glucose, amino acids, fatty acids) enter the bloodstream through the small intestine. Cells use these with oxygen in cellular respiration (mitochondria’s power plants) to produce ATP (energy currency). 

Carbohydrates → Glucose = Instant energy 

Fats → Fatty acids = Long-term energy storage 

Proteins → Amino acids = Backup energy (when carbs/fats are low) 

This energy fuels everything from muscle movement to brain function. Excess glucose gets stored as glycogen (liver/muscles) or fat. 

Example: Eating rice (carbs) → glucose → ATP for your morning run!

Q10. Define rumination and ruminants. Give three examples of ruminants.

Answer. Ruminants are herbivores with four-chambered stomachs that digest tough plant cellulose through bacterial fermentation. Examples include: 

– Cows 

– Goats 

– Sheep 

– Deer 

They regurgitate and rechew food (cud) for complete digestion.

Q11 . Describe the structure and function of a Ruminant Stomach.

 Structure 

Answer. The four chambers are: 

1. Rumen (fermentation vat) 

2. Reticulum (forms cud) 

3. Omasum (water absorption) 

4. Abomasum (true acid stomach) 

This specialized system allows efficient breakdown of fibrous plant material that most animals cannot digest.