1. Classify according to food type
tiger, cow, vulture, bacteria, deer, goat, human, fungus, lion, sparrow, buffalo, frog, cockroach, tick
Answer. Herbivores: cow, deer, goat, buffalo
- Carnivores (predators): tiger, lion, frog
- Scavenger (carnivore): vulture
- Omnivores: human, sparrow, cockroach
- Decomposers/Saprophytes: bacteria, fungus
- Parasite (ectoparasite): tick
2. Match the pairs
| Group ‘A’ | Group ‘B’ |
| (1) Parasitic plant | (a)Mushroom |
| (2) Insectivorous plant | (b) Lichen |
| (3) Saprophytic plant | (c) Drosera |
| (4) Symbiotic Plant | (d)Cuscuta |
Group ‘A’ → Group ‘B’
(1) Parasitic plant → (d) Cuscuta
(2) Insectivorous plant → (c) Drosera
(3) Saprophytic plant → (a) Mushroom
(4) Symbiotic plant → (b) Lichen
3. Answer the following questions in your own words
(a) Why do living organisms need nutrition?
Answer. Living organisms need nutrition to obtain energy for life processes (movement, growth, reproduction, repair) and to supply raw materials for building and replacing cells and tissues. Nutrients such as carbohydrates and fats provide energy, proteins supply amino acids for body building, minerals and vitamins regulate enzyme actions and immunity, and water acts as a medium for reactions and transport. Without a continuous supply of balanced nutrients, metabolism slows, immunity weakens, and normal development cannot occur. Thus, nutrition maintains homeostasis and enables organisms to survive and adapt in their environment.
(b) Explain the process of production of food in plants.
Answer: Green plants make food by photosynthesis in chloroplasts. Chlorophyll traps sunlight. Roots absorb water and minerals; leaves take in carbon dioxide through stomata. Using light energy, plants convert carbon dioxide and water into glucose and oxygen (released to air). The overall reaction is:
CO₂ + H₂O —(light, chlorophyll)→ C₆H₁₂O₆ + O₂.
Glucose is used immediately for energy, converted to sucrose for transport, or stored as starch in leaves, stems, roots, and seeds. Minerals like nitrate and phosphate help synthesize proteins and nucleic acids. Hence, photosynthesis is the basic source of food for almost all life.
(c) What is meant by parasitic plants? Name their different types with examples of each.
Answer. Parasitic plants obtain water/food from another plant (host) through special organs called haustoria. Types:
- Total (holo) parasites – lack chlorophyll; fully dependent on host.
• Stem parasite: Cuscuta (dodder).
• Root parasite: Rafflesia, Orobanche. - Partial (hemi) parasites – have chlorophyll; take mainly water/minerals from the host.
• Stem parasite: Viscum (mistletoe).
• Root parasite: Santalum album sandalwood, Striga.
They weaken hosts by stealing resources and reducing yield.
(d) Explain the various steps of nutrition in animals.
Answer. The steps are:
- Ingestion – taking food into the body (mouth, sucker, etc.).
- Digestion – mechanical and enzymatic breakdown of complex food to soluble molecules (stomach, intestine).
- Absorption – digested nutrients pass through intestinal walls into blood/lymph.
- Assimilation – cells use absorbed nutrients for energy, growth, and repair; excess is stored as glycogen/fat.
- Egestion – elimination of undigested waste through the anus/other openings.
6. These coordinated steps ensure energy supply and tissue maintenance.
(e) Name some unicellular organisms in which all life processes take place within their unicellular body.
Answer. Amoeba, Paramecium, Euglena, Yeast (unicellular fungus), and many bacteria. In each, a single cell performs all essential functions, including nutrition, respiration, excretion, movement, and reproduction.
4. Give reasons
(a) Insectivorous plants are attractively coloured.
Answer. They grow in nitrogen-poor habitats (bogs, marshes). Bright colours, scent, and nectar attract insects, which they trap and digest to obtain nitrogen and minerals lacking in the soil.
(b) Butterflies have a long tube-like proboscis.
Answer. Butterflies feed on liquid nectar deep inside flowers. The long, coiled proboscis works like a straw, allowing them to suck nectar efficiently without damaging the flower—an adaptation to their liquid diet.
5. Prepare and complete the flowchart according to type of nutrition
Nutrition
→ Plants: Autotrophic (e.g., mango), Insectivorous (e.g., Drosera, Nepenthes), Parasitic (e.g., Cuscuta), Saprophytic (e.g., mushroom).
→ Animals: Parasitic → Ectoparasitic (live on body surface: louse, tick) and Endoparasitic (live inside body: tapeworm, roundworm).
(If your book shows fewer boxes, at minimum fill: Plants—Autotrophic, Insectivorous; Animals—Parasitic → Ectoparasitic / Endoparasitic.)
6. Think and answer
(a) We prepare a variety of foodstuffs and dishes at home. Are we then autotrophic organisms?
Answer. No Autotrophs make food from inorganic substances using light (photosynthesis) or chemicals (chemosynthesis). Humans only process food made by plants/animals; we cannot convert CO₂ and water into glucose. Hence, we are heterotrophs.
(b) Which organisms are greater in number—autotrophs or heterotrophs? Why?
Answer. By number of species and individuals, heterotrophs are greater because they include vast groups—animals, fungi, most bacteria, many protists—adapted to countless niches. Autotrophs are comparatively fewer major groups (plants, algae, cyanobacteria). However, note: in biomass, autotrophs (especially plants and marine phytoplankton) form the primary producers that support all food chains.
(c) The number of heterotrophs found in desert regions is smaller. However, they are found in greater numbers in the sea. Why is this so?
Answer. Deserts have scarce water and very low primary productivity—few plants → limited food and shelter → few heterotrophs can survive. Seas contain abundant phytoplankton and nutrients (especially in productive zones), giving high primary productivity, stable water, and vast habitats; therefore, heterotrophs flourish zooplankton, fish, and marine mammals.
(d) What damage or harm do ectoparasitic and endoparasitic animals cause?
Answer. Ectoparasites (lice, ticks, mites): itching, skin injury, blood loss, reduced growth, and transmission of diseases (e.g., tick-borne fevers).
- Endoparasites (tapeworm, roundworm): steal nutrients → malnutrition, anemia, intestinal blockage, tissue damage; may release toxins and cause weakness. Heavy infestations can be serious if untreated.
(e) Why is plant food not produced in any other parts of the plant except the green ones?
Answer. Only green parts (leaves, soft green stems) have chloroplasts containing chlorophyll, which absorbs light energy to drive photosynthesis. Non-green organs (roots, woody stems, flowers/fruits before greening) lack chloroplasts or have too few; therefore, they cannot synthesize food and depend on sugars transported from leaves.