Living Creatures: Exploring their CharacteristicsClass 6 Science NCERT Solutions
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Q2Let us enhance our learning
The table on the next page shows some data. Study the data and try to find out examples appropriate for the conditions given in the second and third columns. If you think that an example for any of the conditions given below is not possible, explain why.
\begin{tabular}{|l|l|l|l|l|}
\hline S. no. & Does it grow? & Does it respire? & Example & Remarks
\hline 1. & No & No & &
\hline 2. & No & Yes & &
\hline 3. & Yes & No & &
\hline 4. & Yes & Yes & &
\hline
\end{tabular}
Solution
\begin{tabular}{|l|l|l|l|l|}
\hline S. no. & Does it grow? & Does it respire? & Example & Remarks
\hline 1. & No & No & Pencil, Book, Car, Stone & These are non-living things and do not exhibit growth or respiration.
\hline 2. & No & Yes & Not possible & Respiration is an essential characteristic of living beings, and living beings also grow. An entity that respires but does not grow contradicts the definition of living beings provided in the text.
\hline 3. & Yes & No & Not possible & Growth is a characteristic of living beings, and all living beings respire. An entity that grows but does not respire contradicts the definition of living beings provided in the text.
\hline 4. & Yes & Yes & Plant, Pigeon, Dog, Human & These are living beings and exhibit both growth and respiration as essential life processes.
\hline \end{tabular}
\hline 1. & No & No & Pencil, Book, Car, Stone & These are non-living things and do not exhibit growth or respiration.
\hline 2. & No & Yes & Not possible & Respiration is an essential characteristic of living beings, and living beings also grow. An entity that respires but does not grow contradicts the definition of living beings provided in the text.
\hline 3. & Yes & No & Not possible & Growth is a characteristic of living beings, and all living beings respire. An entity that grows but does not respire contradicts the definition of living beings provided in the text.
\hline 4. & Yes & Yes & Plant, Pigeon, Dog, Human & These are living beings and exhibit both growth and respiration as essential life processes.
\hline \end{tabular}
Q3Let us enhance our learning
You have learnt that different conditions are required for seed germination. How can we use this knowledge for proper storage of grains and pulses?
Solution
Seeds require specific conditions like water and air for germination. If these conditions are met, the seeds will sprout. For proper storage of grains and pulses, it is essential to prevent them from germinating or getting spoiled. Therefore, to ensure proper storage, grains and pulses should be kept in dry conditions, meaning they should not be exposed to moisture or excess water. They should also be stored in airtight containers or environments where air circulation is limited, thus reducing the availability of air for germination and preventing the growth of microorganisms that thrive in moist and airy conditions. This knowledge helps in preserving the grains and pulses for longer durations without spoilage.
Q4Let us enhance our learning
You have learnt that a tail is present in a tadpole but it disappears as it grows into a frog. What is the advantage of having a tail in the tadpole stage?
Solution
In the tadpole stage, a frog lives entirely in water. The tail is a special feature that helps the tadpole swim efficiently in water. Tadpoles use their tails for propulsion, allowing them to move through their aquatic habitat to find food and escape predators. As the tadpole develops into a froglet and then an adult frog, it develops strong legs for jumping and swimming, and its habitat shifts to both water and land, making the tail unnecessary, so it gradually disappears.
Q5Let us enhance our learning
Charan says that a wooden log is non-living as it cannot move. Charu counters it by saying that it is living because it is made of wood obtained from trees. Give your arguments in favour or against the two statements given by Charan and Charu.
Solution
Let us analyze the statements based on the characteristics of living beings:
Arguments regarding Charan's statement:
Charan says a wooden log is non-living as it cannot move. This statement is partially correct. While movement is a characteristic of living beings, a wooden log, once cut from a tree, is indeed non-living. It does not exhibit other essential characteristics of living beings such as respiration, growth, reproduction, excretion, or response to stimuli. Therefore, its inability to move is one indicator of its non-living nature.
Arguments regarding Charu's statement:
Charu counters by saying it is living because it is made of wood obtained from trees. This statement is incorrect. A tree, when alive, is a living being. However, once a tree is cut down, the wood obtained from it is no longer performing the life processes. The cells in the wood are dead, and the log cannot grow, respire, reproduce, excrete, or respond to stimuli. Therefore, although its origin is from a living organism, the wooden log itself is considered non-living.
Q6Let us enhance our learning
What are the similarities and distinguishing features in the life cycles of a mosquito and a frog?
Solution
Similarities in life cycles of a mosquito and a frog:
- Metamorphosis: Both mosquitoes and frogs undergo significant changes in their body shape and structure during their life cycles, a process called metamorphosis.
- Aquatic Egg Stage: Both start their life cycle as eggs laid in water.
- Larval Stage: Both have a distinct larval stage (larva for mosquito, tadpole for frog) that lives in water and looks very different from the adult.
- Pupa-like Stage: Both have a stage where they develop further before becoming an adult. Mosquitoes have a pupa stage, while frogs have a froglet stage that is transitional.
- Growth and Development: Both show growth and development through various stages from egg to adult.
- Reproduction: Both reproduce to continue their kind.
Distinguishing features in life cycles of a mosquito and a frog:
- Number of Stages: A mosquito's life cycle typically has four distinct stages: egg, larva, pupa, and adult. A frog's life cycle has stages like egg, embryo, tadpole (early and late), froglet, and adult frog.
- Pupa Stage: Mosquitoes have a non-feeding pupal stage, which is distinct in form. Frogs do not have a true pupa stage like insects; their tadpole gradually transforms into a froglet.
- Habitat Change: While both start in water, the degree of habitat change differs. Adult mosquitoes are flying insects, while adult frogs live both in water and on land.
- Appearance of Larval/Adult Forms: Mosquito larvae (wigglers) are worm-like, and adults are flying insects. Tadpoles are fish-like with gills and a tail, while adult frogs are amphibians with legs and no tail.
- Respiration in Aquatic Stages: Mosquito larvae and pupae come to the water surface to breathe air. Tadpoles breathe using gills in water.
Q7Let us enhance our learning
A plant is provided with all the conditions suitable for its growth (Fig. 10.9). Draw what you expect to see in the shoot and the root of the plant after one week. Write down the reasons.
Solution
Expected Drawing (Description):
If the pot is kept along the ground (horizontally as in Fig. 10.9), after one week:
- The shoot of the plant will bend and grow upwards, away from the ground.
- The root of the plant will bend and grow downwards, into the soil.
Reasons:
- Shoot Growth (Upwards): Shoots exhibit negative geotropism (grow away from gravity) and positive phototropism (grow towards light). Even though the pot is horizontal, the shoot will orient itself to grow vertically upwards, responding to gravity and seeking sunlight.
- Root Growth (Downwards): Roots exhibit positive geotropism (grow towards gravity). Regardless of the initial orientation of the plant, the roots will always grow downwards into the soil, following the pull of gravity to anchor the plant and absorb water and nutrients.
Q8Let us enhance our learning
Tara and Vijay set up the experiment shown in the picture (Fig. 10.10). What do you think they want to find out? How will they know if they are correct?
Solution
What they want to find out:
Tara and Vijay want to investigate the effect of unidirectional light on the growth direction of the plant's shoot and root. Specifically, they want to observe if the shoot grows towards the light source (phototropism) and if the root continues to grow downwards (geotropism) even when light is coming from only one side.
How they will know if they are correct:
They will know if their observations match the expected behavior of plants:
- If the shoot bends and grows towards the small circular hole from which light is entering, it will confirm that shoots are positively phototropic (grow towards light).
- If the root continues to grow downwards into the blotting paper/water, it will confirm that roots are positively geotropic (grow towards gravity) regardless of the direction of light.
Q9Let us enhance our learning
Design an experiment to check if temperature has an effect on seed germination.
Solution
Aim: To investigate the effect of temperature on seed germination.
Materials: Four identical pots, garden soil, bean seeds, water, a warm location (e.g., room temperature), a cold location (e.g., refrigerator), a moderately warm location (e.g., near a window but not direct scorching sun).
Procedure:
- Take four identical pots filled with garden soil. Sow four bean seeds in each pot.
- Ensure that each pot receives a moderate and consistent amount of water daily, keeping the soil moist but not waterlogged. This ensures that water availability is not a variable.
- Place the pots in different temperature conditions:
- Pot A: Place in a warm location (e.g., typical room temperature, around ). This will serve as a control/optimal condition.
- Pot B: Place in a cold location (e.g., refrigerator, around ). This will test low temperatures.
- Pot C: Place in a moderately warm location (e.g., a slightly warmer spot in the room, around ). This will test slightly higher temperatures.
- Pot D: Place in a very warm location (e.g., near a heater, ensuring it is not excessively hot to kill the seeds, perhaps around ). This will test higher temperatures.
- Ensure all pots receive adequate air, for example, by not compacting the soil too much.
- Observe the pots regularly for days and record the number of seeds that germinate (sprout) in each pot.
Observation: Note the time taken for germination and the percentage of seeds germinated in each pot.
Conclusion: By comparing the germination rates and times across the different temperature conditions, one can conclude whether temperature has an effect on seed germination and identify the optimal temperature range for the given seeds.