Class 10 Science Lesson 3

Exercise

1. Choose the correct options for the questions below.

a) Which bee contains only 16 chromosomes?
i. Queen bee
ii. Worker bee
iii. Drone bee
iv. Queen and worker bee

Answer: iii. Drone bee

b) From where is royal jelly produced?
i. from the gland at the head of queen bee
ii. from the gland at the head of drone
iii. from the gland at the head of worker bee
iv. from the salivary gland of worker

Answer: iv. from the salivary gland of worker

c) Which bee is formed when the larva is fed royal jelly continuously?
i. queen
ii. drone
iii. workers
iv. queen and worker bee

Answer: i. queen

d) Which stage of the bee is shown in the given diagram?
i. egg
ii. larva
iii. pupa
iv. adult

Answer: iii. pupa

e) Why is honey bee called a social insect?
i. It produces honey.
ii. It helps in pollination in plants.
iii. It lives in colony
iv. It is domesticated insect.

Answer: iii. It lives in colony

f) When the pollen baskets in the legs of worker bees are broken by certain means, which of the following functions cannot be performed by them?
i. collecting nectar
ii. constructing brood cell
iii. feeding royal jelly to larva
iv. collecting pollen from flower

Answer: iv. collecting pollen from flower

g) Which of the following is the characteristic of the drone bee?
i. haploid, sterile, medium sized, hairy
ii. haploid, fertile, medium sized, hairy
iii. diploid, sterile, medium sized, smooth
iv. diploid, fertile, medium sized, hairy

Answer: ii. haploid, fertile, medium sized, hairy

h) Where does the queen bee store the sperms received from the drone bee after the nuptial flight?
i. pollen sac
ii. ovary
iii. sperm sac
iv. egg sac

Answer: iii. sperm sac (also called spermatheca)

2. Differentiate: 

Aspect	Drone Bee	Worker Bee
Chromosome number	Haploid (16 chromosomes)	Diploid (32 chromosomes)
Sex	Male	Female
Function	Fertilizes queen	Performs all hive duties (foraging, nursing, cleaning)
Size	Larger than worker	Smaller than drone
Reproductive ability	Fertile	Sterile
Body features	Hairy, medium-sized	Hairless, smaller, with pollen baskets

 

Aspect		Queen Bee		Worker Bee
Chromosome number		Diploid (32 chromosomes)		Diploid (32 chromosomes)
Role		Lays eggs (main reproductive female)		Non-reproductive female, hive worker
Size		Largest in the colony		Smaller than queen
Lifespan		Longer (up to several years)		Shorter (few weeks to months)
Feeding in larva stage		Fed royal jelly continuously		Fed royal jelly only briefly

 

Aspect		Queen Bee		Drone Bee
Chromosome number		Diploid (32 chromosomes)		Haploid (16 chromosomes)
Sex		Female		Male
Role		Reproduction (lays eggs)		Fertilizes queen
Body size		Largest		Medium-sized
Reproductive organ		Developed ovaries		Developed testes
Lifespan		Longer		Shorter

3. Give reasons:

a) Why is honey bee called a social insect?

Answer: Honey bee is called a social insect because it lives in large organized groups called colonies where each bee performs specific tasks for the benefit of the entire colony. They work cooperatively in collecting food, caring for young ones, and protecting the hive, showing a high level of social behavior.

b) Why is pasture land required for bee farming?

Answer: Pasture land is important for bee farming because it provides a rich source of flowers from which bees collect nectar and pollen. Without abundant flowering plants, bees cannot gather enough food to produce honey and sustain the colony.

c) Why does the drone die after mating?

Answer: The drone dies after mating because during copulation, its reproductive organs detach from its body. This injury is fatal, so the drone dies shortly after successfully fertilizing the queen.

d) Why are bees called multipurpose insects?

Answer: Bees are called multipurpose insects because they serve many useful roles. They produce honey and beeswax, which are valuable products for humans. Additionally, they play a vital role in pollination, helping plants to reproduce, which increases agricultural productivity.

4. Answer the following questions:

a) Write the various types of bees found in the hive.

Ans: The three types are:

• Queen bee
• Worker bees
• Drone bees

b) What is the function of the drone bee? 

Ans: The function of the drone bee is to mate with the queen bee during the nuptial flight. Drones do not have stingers and are not involved in tasks such as foraging or nest building. 

c) If the queen bee dies for some reason, who will control the hive?

Ans: The worker bees will control the hive until a new queen is raised.

d) How does the queen bee control other members of the hive?

Ans: The queen produces pheromones (chemical signals) that regulate the activities and behavior of the worker bees.

e) Write the uses of honey.

Ans: Honey is used as a nutritious food by humans and bees. It also has medicinal properties such as healing wounds and soothing coughs. Moreover, honey is used in cosmetics and skincare products because of its moisturizing and antibacterial qualities.

f) Describe the structure of the queen bee.

Ans: The honey bee has a well-defined and segmented body, which is divided into three main parts: head, thorax, and abdomen.

1. Head:
   The head bears a pair of compound eyes, three simple eyes (ocelli), and a pair of antennae that help in smelling and sensing vibrations. It also includes mouthparts adapted for both biting and sucking nectar.
2. Thorax:
   The thorax is the middle part and is responsible for movement. It bears three pairs of legs and two pairs of wings. The legs also have special structures for collecting pollen.
3. Abdomen:
   The abdomen contains important internal organs, such as those for digestion, reproduction, and stinging. The queen bee and worker bees have stingers, whereas drones do not. Wax glands are also located in the abdomen of worker bees.

g) Mention the functions of the worker bee.

Ans: The worker bee is the most active and hardworking member of the hive. All worker bees are female but do not reproduce. Their duties vary according to their age:

1. Cleaning the hive 
2. Feeding the queen, drones, and larvae
3. Wax production
4. Guarding the hive 

h) Explain how the division of labour occurs in bees.

Ans: In a honey bee colony, division of labour is based on age and caste. Each bee performs specific duties that contribute to the overall functioning of the hive. This division ensures efficiency and harmony within the colony.

1. Queen Bee – The only fertile female, the queen’s main role is to lay eggs. She can lay up to 2,000 eggs per day and also secretes pheromones that regulate colony behavior.
2. Drone Bee – Drones are male bees. Their sole function is to mate with a virgin queen during the mating flight. After mating, drones die.
3. Worker Bees – These sterile female bees perform all other tasks. Their roles change with age:
   • Days 1–3: Cleaning the hive and brood cells.
   • Days 4–10: Feeding larvae and the queen.
   • Days 11–20: Producing wax and building combs, guarding the hive.

i) Explain the life cycle of a honey bee.

Ans: The life cycle of a honey bee is a fascinating process that involves complete metamorphosis, meaning the bee undergoes four distinct developmental stages: egg, larva, pupa, and adult. 

1. Egg Stage

The life cycle begins when the queen bee lays an egg in a wax cell of the honeycomb. She lays thousands of eggs, one in each cell. These eggs are tiny, oval-shaped, and white, resembling a small grain of rice. The egg remains in this stage for about three days. Whether an egg will become a queen, worker, or drone depends on two factors: whether the egg is fertilized or unfertilized, and the type of food the larva receives after hatching.

• Fertilized eggs develop into female bees (either workers or queens).
• Unfertilized eggs develop into male bees (drones) through a process called parthenogenesis.

2. Larva Stage

After three days, the egg hatches into a larva. The larva looks like a small white worm and has no legs, wings, or eyes. Nurse bees feed the young larva with a highly nutritious substance called royal jelly for the first few days. After that:

• Worker larvae are fed a mixture of pollen and nectar (called bee bread).
• Queen larvae continue to receive royal jelly throughout the larval stage, which causes them to develop into fertile queens.

The larval stage lasts about five to six days, during which the larva eats continuously and grows rapidly, shedding its skin several times.

3. Pupa Stage

Once the larva has grown enough, the cell is capped with wax by the worker bees, and the larva spins a cocoon around itself to enter the pupal stage. During this period, the bee undergoes complete transformation (metamorphosis). The following changes occur:

• The body segments become visible.
• Wings, legs, eyes, and other organs start developing.
• The bee’s final shape starts forming.

The duration of the pupal stage differs by caste:

• Queen bee: about 7 days
• Worker bee: about 12 days
• Drone bee: about 14 days

4. Adult Stage

After completing the pupal stage, the adult bee emerges by chewing through the wax cap. The time taken from egg to adult depends on the type of bee:

• Queen bee: 16 days
• Worker bee: 21 days
• Drone bee: 24 days

Once emerged:

• Worker bees perform various duties based on their age (cleaning, nursing, guarding, foraging, etc.).
• Drone bees live only to mate with a virgin queen and die shortly after mating.
• Queen bee is responsible for laying eggs and maintaining the unity of the hive by releasing pheromones.

j) What is the process called in which a drone is developed from an unfertilized egg?

Ans: The process is called parthenogenesis.

In honey bees, drones (male bees) are produced from unfertilized eggs laid by the queen. This means there is no contribution of male sperm in the development of drones. This is a natural form of asexual reproduction and is unique to certain insects like honey bees. As a result, drones have only half the number of chromosomes (haploid) compared to worker bees and queens (diploid).

k) When a farmer practises bee farming, then income of other farmers in that locality also increases. Justify your reason.

Ans: When a farmer engages in bee farming (apiculture), bees not only produce honey and wax but also act as pollinators. As they travel from flower to flower collecting nectar and pollen, they unintentionally pollinate various crops, which helps other farmers in the area as well.

Justification:

1. Increased crop yield – Pollination leads to better fertilization of crops, which improves both quantity and quality.
2. Enhanced fruit setting – Fruits and vegetables develop more completely due to proper pollination.
3. Mutual benefits – Even if other farmers don’t keep bees, their crops benefit from nearby hives due to bee movement.

Thus, bee farming improves the overall agricultural productivity in the locality, leading to increased income for multiple farmers, not just the beekeeper.

l) Due to the problem of pasture land in the beekeeping area, beekeepers shifted the bees from there. After that, there was a reduction in the yield of mustard crops of nearby farmers. Based on this, explain the relationship between beekeeping and agricultural production.

Ans: This situation clearly shows that beekeeping and agriculture are closely interlinked. Bees are the most effective natural pollinators, and their presence significantly enhances the yield of flowering crops like mustard, sunflower, fruits, and vegetables.

Explanation:

1. When beekeepers removed the bees due to pasture land problems, pollination reduced, as bees were no longer available to transfer pollen between mustard flowers.
2. Mustard plants depend heavily on cross-pollination, and the absence of bees led to poor fertilization and a decline in crop yield.
3. This indicates that bees are not only important for honey production but also for increasing agricultural productivity.

Hence, beekeeping is a vital component of sustainable agriculture. It not only provides additional income through bee products but also improves the output of crop farming by ensuring efficient pollination.

m) Look at the concept map and complete it.

• • Top left box (→ from Parthenogenesis): Drone Bee
  • Bottom right box (↓ from Fertilization): Worker Bee
  • Top right box (→ from Fertilization labeled “Fertile”): Queen Bee