CLASS 8 · SCIENCE · CHAPTER 13
Simple answers to the opening prompts, chapter concepts, all twelve end questions, and all five projects.
32 worked answers · short steps first, explanations when you need them
Textbook pages 210
Question Opening prompt 1
The non-living planet would remain, but living organisms and their effects would be gone.
The non-living planet would remain, but living organisms and their effects would be gone.
Question Opening prompt 2
Suitable conditions, reproduction, variation, and connected ecosystems help life continue.
Suitable conditions, reproduction, variation, and connected ecosystems help life continue.
Question Opening prompt 3
Dogs are mammals whose young develop inside the mother; chicks develop in eggs.
Dogs are mammals whose young develop inside the mother; chicks develop in eggs.
Question Opening prompt 4
No. Plants need suitable light, air, temperature, nutrients, and water too.
No. Plants need suitable light, air, temperature, nutrients, and water too.
Textbook pages 212–225
Question Activity 13.1
Liquid water, atmosphere, suitable temperature, gravity, ozone, and magnetic field.
Liquid water, atmosphere, suitable temperature, gravity, ozone, and magnetic field.
Question Activity 13.2
Venus’s thick carbon dioxide atmosphere traps more heat.
Venus’s thick carbon dioxide atmosphere traps more heat.
Question Habitable zone
It is the distance range where liquid water may exist; Earth is in that range.
It is the distance range where liquid water may exist; Earth is in that range.
Question Earth’s size
Earth’s gravity helps keep its atmosphere from escaping into space.
Earth’s gravity helps keep its atmosphere from escaping into space.
Question Protective shields
Ozone blocks much UV; the magnetic field deflects many charged particles.
Ozone blocks much UV; the magnetic field deflects many charged particles.
Question Earth systems
Air, water, solid Earth, and life are the atmosphere, hydrosphere, geosphere, and biosphere.
Air, water, solid Earth, and life are the atmosphere, hydrosphere, geosphere, and biosphere.
Question Vegetative propagation
A plant part can grow into a new plant; this is vegetative propagation.
A plant part can grow into a new plant; this is vegetative propagation.
Question Climate and life
A change such as deforestation can affect soil, water, climate, and wildlife.
A change such as deforestation can affect soil, water, climate, and wildlife.
Question Reproduction
Offspring inherit similarities, while gene mixing can create variation.
Offspring inherit similarities, while gene mixing can create variation.
Question Threats to life
Climate change, biodiversity loss, and pollution.
Climate change, biodiversity loss, and pollution.
Question Protecting Earth
Save resources, reduce waste and pollution, and protect habitats.
Save resources, reduce waste and pollution, and protect habitats.
Textbook pages 226–227
Question 1
Option (iii).
Option (iii).
Question 2
Option (ii).
Option (ii).
Question 3
Option (ii).
Option (ii).
Question 4
Option (iv).
Option (iv).
Question 5
Seeds may arrive by wind, animals, or water; rain, light, air, and nutrients help them grow.
Seeds may arrive by wind, animals, or water; rain, light, air, and nutrients help them grow.
Question 6
It can raise heat, reduce wildlife, increase erosion and runoff, and affect water supply.
It can raise heat, reduce wildlife, increase erosion and runoff, and affect water supply.
Question 7
Past climate changes occurred, but today’s rapid warming is strongly driven by human greenhouse gases.
Past climate changes occurred, but today’s rapid warming is strongly driven by human greenhouse gases.
Question 8
Satellites and communication could be affected, and radiation exposure could rise.
Satellites and communication could be affected, and radiation exposure could rise.
Question 9
Air and pressure, water, and warmth/radiation protection; a safe atmosphere may be hardest.
Air and pressure, water, and warmth/radiation protection; a safe atmosphere may be hardest.
Question 10
Climate change and land-use changes may contribute; save water and use climate-suited crops.
Climate change and land-use changes may contribute; save water and use climate-suited crops.
Question 11
Life would lose air and protection; temperatures would become extreme and liquid water unstable.
Life would lose air and protection; temperatures would become extreme and liquid water unstable.
Question 12
Potato, ginger, onion, sugarcane, and money plant.
Potato, ginger, onion, sugarcane, and money plant.
Textbook pages 227–228
Question Project 1
Include air, water, light, suitable temperature, nutrients, and a way to recycle materials.
Include air, water, light, suitable temperature, nutrients, and a way to recycle materials.
Question Project 2
Compare simulated lunar soil with garden soil while keeping water, light, and temperature the same.
Compare simulated lunar soil with garden soil while keeping water, light, and temperature the same.
Question Project 3
Colour and scent attract pollinators that carry pollen.
Colour and scent attract pollinators that carry pollen.
Question Project 4
Many eggs raise the chance some survive, but each gets less care.
Many eggs raise the chance some survive, but each gets less care.
Question Project 5
More care can protect each young one; laying many eggs can make up for lower survival.
More care can protect each young one; laying many eggs can make up for lower survival.