CBSE > Class 07 > Science | CBSE Board | Homework Help

a fuse is an electrical safety device that operates to provide overcurrent protection of an electrical circuit. Its essential component is a metal wire or strip that melts when too much current flows through it, thereby stopping or interrupting the current. A fuse is an automatic means of removing power from a faulty system; often abbreviated to ADS (Automatic Disconnection of Supply). Circuit breakers can be used as an alternative to fuses.

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Define in detail what is stomata

Posted by Ryan Sam 6 years ago

CBSE > Class 07 > Science

2 answers

Akash Sharma 6 years ago

Small openings present on the underside of the leaves is stomata. Functions of stomata: (i) It helps in exchange of gases (ii) It helps in transpiration

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Yogita Ingle 6 years ago

Stomata are tiny pores present on the surface of a leaf.

Functions of stomata:

(a) Stomata help in the exchange of gases.

(b) Evaporation of water from the leaf surface occurs through stomata.

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Write in short types of images formed by concave and convex mirror and lens relativaly

Posted by Sunita Kulhari 6 years ago

CBSE > Class 07 > Science

1 answers

Meghna Thapar 5 years, 11 months ago

Image formation by a concave mirror for different positions of the object:

Images formed by a Convex Mirror:

Position of object	Position of image	Size of image	Nature of image
At infinity	At focus F behind the mirror	Highly diminished, point sized	Virtual and erect
Anywhere between infinity and the pole of the mirror	Between P and F behind the mirror	Diminished	Virtual and erect

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Difference between concave and convex mirror

Posted by Sunita Kulhari 6 years ago

CBSE > Class 07 > Science

1 answers

Yogita Ingle 6 years ago

Concave mirror	Convex mirror
A spherical mirror whose reflecting surface is curved inwards is called a concave mirror.	A spherical mirror whose reflecting surface is curved outwards is called a convex mirror.
A parallel beam of light falling on this mirror converges at a point after reflection.	A parallel beam of light falling on this mirror appears to diverge from a point after reflection.
It is also called a converging mirror.	It is also called a diverging mirror.
It has a real focus.	It has a virtual focus.
The magnification of a concave mirror can be greater, equal or less than 1.	The magnification of a convex mirror is always less than 1.
These mirrors are used as reflectors in projectors, light-house headlights, searchlights, etc.	These mirrors are used as rear-view mirrors in cars and motorcycles, as they enable the driver/rider to view the road and vehicles behind.

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Sun light is a mixture of different colors. Just use the activity to prove it?

Posted by Sunita Kulhari 6 years ago

CBSE > Class 07 > Science

1 answers

Anita Devi 6 years ago

You can use a prism. A prism splits light into seven colours.

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Why is photosynthesis done in plant

Posted by Nishant Sinkar 6 years ago

CBSE > Class 07 > Science

2 answers

Nishant Sinkar 6 years ago

It's wrong answer

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Yogita Ingle 6 years ago

The process by which plants make their own food in the presence of sunlight, carbon-dioxide present in air, water, minerals and chlorophyll present in leaves is termed as photosynthesis.

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Name an instrument heat from the sun

Posted by Prasad Sadhye 6 years ago

CBSE > Class 07 > Science

1 answers

Meghna Thapar 5 years, 11 months ago

Pyrheliometer is an instrument for measuring heating effect of sun. A pyrheliometer is a device used to quantify the direct sunbeam of solar insolation. Sun rays enter the windowpanes and are oriented onto an instrument called a thermopile. A thermopile consists of thermocouples, which are connected in series. These are also, commonly referred to as Parallel. A thermopile transmutes thermal energy into electric signals. A pyrheliometer is a measuring instrument, which uses a formula to convert signal voltage to calculate watts per squared meter.

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Distance time graph

Posted by Aastha Chinu 6 years ago

CBSE > Class 07 > Science

1 answers

Meghna Thapar 5 years, 11 months ago

A distance-time graph shows how far an object has travelled in a given time. It is a simple line graph that denotes distance versus time findings on the graph. Distance is plotted on the Y-axis. Time is plotted on the X-axis.

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Define with diagram of concave and conve×

Posted by Manjunatha Manjunatha 6 years ago

CBSE > Class 07 > Science

1 answers

Baldutt Sharma 6 years ago

Ffggyyyy

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Posted by Manjunatha Manjunatha 6 years ago

CBSE > Class 07 > Science

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What is the definition of cell

Posted by Kiran Kumar Sangadi 6 years ago

CBSE > Class 07 > Science

2 answers

Any Khan 6 years ago

It is a device which is used as a source of electric current

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Naman Ahden 6 years ago

According to electricity, it is an electronic device helps to run electronic items with a cathode(+ve terminal of cell) and anode(-ve terminal of cell). According to our body, a cell is a basic structural and functional unit of life and is divided into 3 parts_ erthrocytes [ red blood cells or RBCs], leukocytes [ white blood cells or WBC] and thrombocytes [platelets]

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Define a year

Posted by Yogender Kashyap 6 years ago

CBSE > Class 07 > Science

1 answers

Divyansh Jain 6 years ago

A year occurs when earth completes its revolution. A year has 365 days. A leap year occurs in every 4 years. It has 366 days.

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How thunderstorm formed

Posted by Ganesh Yadav 6 years ago

CBSE > Class 07 > Science

1 answers

Yogita Ingle 6 years ago

A storm is a disturbed state of environment creating severe weather conditions mainly high speed winds. A thunderstorm is a storm with sound and lightning and typically also heavy rain or hail.

Thunderstorms develop in hot and humid areas.
High temperature in this areas cause hot humid (with water vapours) air to rise up. So, strong upward rising winds with water droplets are generated.
At high altitude, these water drops freeze and fall again towards earth.
Upward movement of air and downward movement of water drops, together, cause lightning and sound.

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What is a blood

Posted by Ruby Kumari 6 years ago

CBSE > Class 07 > Science

5 answers

Any Khan 6 years ago

Blood is a red coloured fluid

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Kasturi Adhau 6 years ago

Blood is a fluid which flows in our body through veins and arteries

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Divyansh Jain 6 years ago

Blood is a specialized bodily fluid that flows in the blood vessels. It contains a protein rich pigment called haemoglobin. Its functions are - 1) It transports oxygen to all parts of the body. 2) It transports digested food from the small intestine to all parts of the body. 3) It transports the liquid wastes to the kidneys for removal from the body.

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Bhanu Sahu 6 years ago

Blood is a liquid substance of our body in that transport the water and minerals in the body

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Naman Ahden 6 years ago

A red-coloured fluid that flows in our body is called a blood

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A simple pendulam takes32s to coplete 20 oscillations. What is the time period of the pendulum

Posted by Angel Bhopala 6 years ago

CBSE > Class 07 > Science

3 answers

Kasturi Adhau 6 years ago

30/20=1.6

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Aman Kumar 6 years ago

Aman

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Piyush Jain 6 years ago

20 / 30

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MQcs 10

Posted by Jaya Gomathi 6 years ago

CBSE > Class 07 > Science

0 answers

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how many types of motion

Posted by Indrajeet Kaushik 6 years ago

CBSE > Class 07 > Science

1 answers

Naman Ahden 6 years ago

There are 7 types of motion-Circular motion, rectilinear motion, periodic motion, non-periodic motion, uniform motion, non-uniform motion, oscillatory motion

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What is the difference between cellular respiration and digestion ?

Posted by Akshara Eswaran 6 years ago

CBSE > Class 07 > Science

1 answers

Meghna Thapar 5 years, 11 months ago

Cellular respiration is a metabolic pathway that breaks down glucose and produces ATP. The term cellular respiration refers to the biochemical pathway by which cells release energy from the chemical bonds of food molecules and provide that energy for the essential processes of life. All living cells must carry out cellular respiration. It can be aerobic respiration in the presence of oxygen or anaerobic respiration. Prokaryotic cells carry out cellular respiration within the cytoplasm or on the inner surfaces of the cells. Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. Digestion helps to obtain the substrate/source which is then used to produce energy via respiration.

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What do you mean by stomatal appartus

Posted by Rishi Mudgal 6 years ago

CBSE > Class 07 > Science

1 answers

Yogita Ingle 6 years ago

Stomata are small pores present in the epidermis of leaves. They regulate the process of transpiration and gaseous exchange. The stomatal pore is enclosed between two bean-shaped guard cells. The inner walls of guard cells are thick, while the outer walls are thin. The guard cells are surrounded by subsidiary cells. These are the specialised epidermal cells present around the guard cells. The pores, the guard cells, and the subsidiary cells together constitute the stomatal apparatus.

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What is pollanition

Posted by Akbar Hussain 6 years ago

CBSE > Class 07 > Science

3 answers

Any Khan 6 years ago

The process of transferring of pollin grains from the stamen to the stigma of a flower is called pollination

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Kasturi Adhau 6 years ago

Transfer of pollen grains from anther to stigma is called pollination

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Gaurav Seth 6 years ago

The process of transfer of pollen from the anther to the stigma of a flower is called pollination.
Pollen grains are transferred to stigma by agents like air or water.
If the pollens are transferred to the stigma of the same flower it is called self pollination.
If the pollens are transferred to the different flowers of the same plant or flowers of a different plant of the same kind it is called cross pollination.

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What is the meaning of assimilation

Posted by Harshit Yadav 6 years ago

CBSE > Class 07 > Science

1 answers

Any Khan 6 years ago

The process of using the absorbed food molecules is called assimilation

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Explain the machenism of breathing

Posted by Sanjay Patwari 6 years ago

CBSE > Class 07 > Science

1 answers

Any Khan 6 years ago

When we breathe our chest goes up (expands ) and goes down (compresses) . During inhalation the ribs move upwards and outwards and the diaphragm moves down .This increases space in the chest cavity due to which air rushes in the lungs and the lungs inflate . Durind exhalation the ribs move downwards and inwards and the diaphragm moves up .This reduces the size of chest cavity which pushes air out of the lungs ......????

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How does earthworm helps farmer

Posted by Anish Shirote. 6 years ago

CBSE > Class 07 > Science

2 answers

Any Khan 6 years ago

It helps the farmer by making the soil fertile

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Laddi Kashyap 6 years ago

Earthwarn help farmer becouse when they grow seed full so small insect eat the leave so earthwarm eat them

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Why are resistive wires made thin and long

Posted by Aatif Mansuri 6 years ago

CBSE > Class 07 > Science

1 answers

Yogita Ingle 6 years ago

The current will flow more easily through a thick wire than through a thin wire of the same material when connected to the same source. This is due to the fact that the resistance of a wire is inversaly proportional to the square of its diameter. A thick wire has a greater diameter and hence lesser resistance making the current to flow through it more easily. On the other hand, a thin wire has smaller diameter and hence greater resistance to the flow of current through it.

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What is soil?How it is important?

Posted by Rajber Yadav 6 years ago

CBSE > Class 07 > Science

1 answers

Yogita Ingle 6 years ago

Mixture of rocks particles, sand and humus is known as soil. Soil supports the growth of plants by holding their roots and supplying water to them.

Importance of Soil

Soil allows the growth of plants. It supplies water and nutrients that are required in the growth of plants.
The soil is the main part of agriculture. Different types of soils support different kinds of crops. Without agriculture, food, shelter and clothing are not possible.
Many microorganisms live in the soil.
Underground water is used for various purposes.

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Difference between sexual and asexual reproduction

Posted by Kanha Sahoo 6 years ago

CBSE > Class 07 > Science

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Difference between fragmentation pollination

Posted by Kanha Sahoo 6 years ago

CBSE > Class 07 > Science

1 answers

Yogita Ingle 6 years ago

Fragmentation	Regeneration
Organisms that are fragmented result in each fragment growing into an individual organism	Regeneration occurs when an organism only regrows a lost limb or any other part of the body.
A new individual emerges from each fragment	No new organisms are formed
Only a few organisms can fragment and form new individuals	All organisms exhibit the ability to regenerate to some degree
Fragmentation is observed in organisms such as flatworms and sponges	Examples of regeneration include regrowing a lost limb, such as the tail of a lizard