JKBOSE/NCERT/CBSE Class 10th Life Science

Monozygotic Twins: Are they Identical?

Merry and Sherry were confused for each other from the day of their birth until they were children, teenagers, and adults. Merry is mistakenly named Sherry almost half the time when they are separated, and Sherry is mistakenly called Merry just as frequently. Even their parents can tell them apart. Since Merry and Sherry were both born from a single fertilized egg, they are monozygotic, or identical, twins. When the embryo split into two cell masses at an early cleavage stage, both cell masses grew into full embryos normally. On April 7, 1955, one infant was called Merry, and the other Sherry.

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Multi –Drug-Resistant Bacteria: A Ticking Timebomb

How serious a threat does the evolution of MDR bacteria pose to human health? Dr. Lee Reichman, on of the world’s leading expert on TB, has reffered to MDR-M, TUBERCULOSIS as a “timebomb”. World, 2 billion people (15 million in the United states) are infected with latent M.tuberculosis. Of these, 8.4 million develop active TB and 2 million die every year. Most of these cases of TB are currently treatable with antibiotics. However, imagine the enormity of the crisis if MDR-M. tuberculosis becomes widespread. Should we begin taking steps to avoid such crisis now –before the “timebomb” explodes?

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                A Walk by the Lake

Within the cities of this society, the lakes and their environs changed. Parks sprang up around the lakes, providing places for recreation, Today, people come to the lakes to swim, cycle, skate or jog. Many come simply to walk. In the city of Minneapolis, for example, all sorts of people can be seen strolling by Lake Harriet on a warm summer evening. Some are descended from the native people who settled in this area when the ice sheets melted. Others are described as African, Asian, European, or South American immigrants. These ethnic groups are differentiated by many physical traits- stature, body build, head shape, facial structure, skin colour and hair texture to name just a few. Within ethnic groups, however, people are more similar and within families, they may even look alike.

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GENETICS AND HEREDITY: Long Answer Type Question Class 10th CHAPTER 14 JKBOSE/NCERT

Analogous organs: These are structures that have similar functions and may superficially resemble each other, but they have different evolutionary origins and do not share a common ancestry.
Analogous organs arise due to convergent evolution, where different species independently evolve similar adaptations in response to similar environmental pressures.
For example, the wings of birds and insects are analogous organs as they serve the same purpose of flying but have different underlying structures and evolutionary origins.
Homologous organs: These are structures that have similar characteristics, both in terms of their structure and evolutionary origin, indicating a common ancestry.
Homologous organs share a similar basic structure but may have different functions in different species.
For example, the forelimbs of humans, bats, cats, and whales have a similar bone structure, indicating a common ancestor, but they have different functions in each species (e.g., grasping, flying, walking, swimming).

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GENETICS AND HEREDITY: SHORT ANSWER TYPE QUESTIONS Class 10th CHAPTER 14 JKBOSE/NCERT

Can the wing of a butterfly and the wing of a bat be considered – homologous organs? Why or why not?
Ans: The wing of a butterfly and the wing of a bat cannot be considered homologous organs. They are analogous organs because they have similar functions (flight) but different evolutionary origins.

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OUR ENVIRONMENT: OBJECTIVE/MULTIPLE CHOICE TYPE QUESTIONS for Class 10th Chapter 10 JKBOSE/NCERT

OUR ENVIRONMENT: OBJECTIVE/MULTIPLE CHOICE TYPE QUESTIONS for Class 10th Chapter 10 JKBOSE/NCERT OBJECTIVE/MULTIPLE CHOICE TYPE QUESTIONS QUESTION 1: The term Ecosystem was introduced by: (a) Miller (b) Haldane (c ) Tansley (d) Darwin Ans: (c) Tansley QUESTION 2. In a food chain, there are: (a) Bidirectional flow of energy. (b) Zig-zag flow of energy. (c)

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OUR ENVIRONMENT: Short Answer Type Questions for Class 10th Chapter 10 JKBOSE/NCERT

Expand the term CFCs
Ans: CFCs stand for chlorofluorocarbons, which are synthetic compounds containing chlorine, fluorine, and carbon. They were commonly used in various industrial applications, including aerosols, refrigerants, and foam-blowing agents. CFCs are known to deplete the ozone layer and have been largely phased out under the Montreal Protocol due to their harmful environmental effects.

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OUR ENVIRONMENT: Short Answer Type Questions for Class 10th Chapter 10 JKBOSE/NCERT

Give any two ways in which biodegradable substances would affect the environment.
Ans: Two ways in which biodegradable substances can affect the environment are:
Nutrient Cycling: Biodegradable substances, when decomposed by microorganisms, contribute to the recycling of nutrients in ecosystems. This nutrient cycling helps maintain the fertility of the soil, promotes plant growth, and supports the overall health and functioning of ecosystems.
Soil Improvement: Biodegradable substances, such as organic waste or compost, can be used to improve soil quality. When added to the soil, these substances enhance its structure, water-holding capacity, and nutrient content. They promote the growth of beneficial microorganisms, improve soil fertility, and support sustainable agricultural practices.

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