Exercises - Chapter 13: Our Home: Earth

Questions and Answers

1. What is one major reason Mars cannot currently support life like Earth?

(i) It has too many volcanoes. (ii) It is too close to the Sun. (iii) It lacks a thick atmosphere and liquid water. (iv) Its magnetic field is too strong.

Answer: (iii) It lacks a thick atmosphere and liquid water.

2. Which of these is an example of geodiversity?

(i) Variety of bird chirping in a forest. (ii) Different landforms like mountains, valleys, and deserts. (iii) Changing weather during monsoons. (iv) Number of different types of fish in a pond.

Answer: (ii) Different landforms like mountains, valleys, and deserts.

3. If the Earth were smaller with the same density, what might happen to its atmosphere?

(i) It would become thicker and hotter. (ii) It would escape into space due to weaker gravity. (iii) It would become frozen. (iv) It would cause stronger winds.

Answer: (ii) It would escape into space due to weaker gravity.

4. In sexual reproduction, why are offspring different from their parents?

(i) They grow in different climates. (ii) They eat different food. (iii) They acquire new instructions after birth. (iv) They get mixed instructions (genes) from both parents.

Answer: (iv) They get mixed instructions (genes) from both parents.

5. You notice tiny green plants growing in cracks on your school wall after the monsoon. Where do you think the seeds came from? What conditions helped these plants grow there?

Answer:

Source of Seeds: The seeds might have been carried by the wind or dropped by birds that ate fruits containing the seeds.
Conditions for Growth: The monsoon rains provided the necessary moisture, and the cracks in the wall trapped enough soil and nutrients to allow the seeds to germinate. Sun-light and air also supported their growth.

6. A city has recently cut down a large patch of forest to build new roads. Discuss the possible effects on local climate and biodiversity.

Answer:

Climate: Fewer trees mean less transpiration, which can lead to reduced rainfall and higher local temperatures (trees provide shade and cooling).
Biodiversity: Many animals and insects lose their habitat and food source, leading to a decrease in the variety of species in the area.
Water: Forests help in groundwater recharge; without them, the water table might drop, and soil erosion could pollute nearby water bodies.

7. If the Earth's magnetic field suddenly disappeared, what problems could arise?

Answer: If the magnetic field disappeared:

Solar Wind Damage: High-energy particles from the Sun (solar wind) would directly hit the atmosphere.
Atmospheric Loss: The solar wind could slowly strip away the Earth's atmosphere.
Ozone Depletion: The ozone layer would be severely damaged, allowing harmful UV rays to reach the surface, causing skin cancers and damaging living cells in all organisms.

8. Imagine you are designing a settlement on Mars. Name three things you would need to recreate from Earth. Which is hardest?

Answer:

Breathable Atmosphere: Recreating an oxygen-rich environment at the right pressure.
Liquid Water: Finding or melting water and keeping it from evaporating in the thin atmosphere.
Radiation Shielding: Protecting humans from cosmic rays and UV radiation.

Hardest to replicate: The magnetic field or a thick stable atmosphere. On Earth, these are maintained by the planet's core and size, which are impossible to "recreate" on a planetary scale using current technology.

9. Discuss five examples of vegetative propagation.

Answer:

Money Plant: Can grow from a stem cutting placed in water or soil.
Potato: Grows from "eyes" (buds) on the tuber.
Ginger: Grows from the rhizome (underground stem).
Rose: Commonly grown from stem cuttings.
Bryophyllum: Produces small plantlets along the margins of its leaves.

Exercises - Chapter 13: Our Home: Earth

5. You notice tiny green plants growing in cracks on your school wall after the monsoon. Where do you think the seeds came from? What conditions helped these plants grow there?

Answer:

Source of Seeds: The seeds might have been carried by the wind or dropped by birds that ate fruits containing the seeds.
Conditions for Growth: The monsoon rains provided the necessary moisture, and the cracks in the wall trapped enough soil and nutrients to allow the seeds to germinate. Sun-light and air also supported their growth.

6. A city has recently cut down a large patch of forest to build new roads. Discuss the possible effects on local climate and biodiversity.

Answer:

Climate: Fewer trees mean less transpiration, which can lead to reduced rainfall and higher local temperatures (trees provide shade and cooling).
Biodiversity: Many animals and insects lose their habitat and food source, leading to a decrease in the variety of species in the area.
Water: Forests help in groundwater recharge; without them, the water table might drop, and soil erosion could pollute nearby water bodies.

7. If the Earth's magnetic field suddenly disappeared, what problems could arise?

Answer: If the magnetic field disappeared:

Solar Wind Damage: High-energy particles from the Sun (solar wind) would directly hit the atmosphere.
Atmospheric Loss: The solar wind could slowly strip away the Earth's atmosphere.
Ozone Depletion: The ozone layer would be severely damaged, allowing harmful UV rays to reach the surface, causing skin cancers and damaging living cells in all organisms.

8. Imagine you are designing a settlement on Mars. Name three things you would need to recreate from Earth. Which is hardest?

Answer:

Breathable Atmosphere: Recreating an oxygen-rich environment at the right pressure.
Liquid Water: Finding or melting water and keeping it from evaporating in the thin atmosphere.
Radiation Shielding: Protecting humans from cosmic rays and UV radiation.

Hardest to replicate: The magnetic field or a thick stable atmosphere. On Earth, these are maintained by the planet's core and size, which are impossible to "recreate" on a planetary scale using current technology.

9. Discuss five examples of vegetative propagation.

Answer:

Money Plant: Can grow from a stem cutting placed in water or soil.
Potato: Grows from "eyes" (buds) on the tuber.
Ginger: Grows from the rhizome (underground stem).
Rose: Commonly grown from stem cuttings.
Bryophyllum: Produces small plantlets along the margins of its leaves.

Chapter 13: Our Home: Earth, a Unique Life Sustaining Planet - Exercises

Exercises - Chapter 13: Our Home: Earth

Questions and Answers

1. What is one major reason Mars cannot currently support life like Earth?

2. Which of these is an example of geodiversity?

3. If the Earth were smaller with the same density, what might happen to its atmosphere?

4. In sexual reproduction, why are offspring different from their parents?

5. You notice tiny green plants growing in cracks on your school wall after the monsoon. Where do you think the seeds came from? What conditions helped these plants grow there?

6. A city has recently cut down a large patch of forest to build new roads. Discuss the possible effects on local climate and biodiversity.

7. If the Earth's magnetic field suddenly disappeared, what problems could arise?

8. Imagine you are designing a settlement on Mars. Name three things you would need to recreate from Earth. Which is hardest?

9. Discuss five examples of vegetative propagation.

On this page

Chapter 13: Our Home: Earth, a Unique Life Sustaining Planet - Exercises

Exercises - Chapter 13: Our Home: Earth

Questions and Answers

1. What is one major reason Mars cannot currently support life like Earth?

2. Which of these is an example of geodiversity?

3. If the Earth were smaller with the same density, what might happen to its atmosphere?

4. In sexual reproduction, why are offspring different from their parents?

5. You notice tiny green plants growing in cracks on your school wall after the monsoon. Where do you think the seeds came from? What conditions helped these plants grow there?

6. A city has recently cut down a large patch of forest to build new roads. Discuss the possible effects on local climate and biodiversity.

7. If the Earth's magnetic field suddenly disappeared, what problems could arise?

8. Imagine you are designing a settlement on Mars. Name three things you would need to recreate from Earth. Which is hardest?

9. Discuss five examples of vegetative propagation.

On this page