Madhyamik Class 10 Life Science Solved Paper 2019

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(d) It is an induced movement of curvature controlled by the direction of the stimulus

(b) Adrenaline decreases cardiac output

(c) 12 pairs

(d) Chromosome and Spindle fibre are not formed

(c) It produces haploid gamete containing hereditary variations

(b) Fragmentation – Spirogyra

(c) Colour of the cotyledon – Yellow

(a) One type

(c) RRyy and Rryy

(b) Struggle between snakes and owls for capturing rats for eating

(c) Inheritance of acquired characters

(d) Honeybee

(d) Chlorinated insecticide

(c) National Park, National Park, Sanctuary, Biosphere Reserve

(b) Asthma

1. Adrenaline
2. DNA
3. Hybridisation
4. Concervate
5. Reserpine
6. Cryopreservation

1. True
2. False. The carpel of a flowering plant is made up of three parts: the stigma, the style, and the ovary. The stigma is the sticky part that collects pollen grains. The style is the long, thin part that connects the stigma to the ovary. The ovary is where the seeds develop.
3. False. The ovum of a human only contains one sex chromosome, which can be either an X chromosome or a Y chromosome. The sex of the baby is determined by the sperm, which can contain either an X chromosome or a Y chromosome.
4. True
5. False. The one-horned rhinoceros is conserved at Kaziranga National Park in Assam, India.
6. True

1 – (c). 2 – (f). 3 – (e), 4 – (b), 5 – (d), 6 – (e)

1. The odd one out is oxytocin. The other three are cranial nerves, while oxytocin is a hormone.
2. Acts as Refactory medium or maintain pressure or, maintain the shape of the eyeball.
3. Grafting : Mango : : Cutting: China Rose.
4. It is caused due to a recessive gene.
5. 1 : 2 : 1.
6. Divergent evolution.
7. Water Pollution.
8. Biosphere Reserve.

Stimuli(sound of the doorbell)
↓
Receptor(the spiral organ of corti)
↓
Sensory neurone (Optic nerve)
↓
Nerve Center (Brain)
↓
Motor neurone (Cranial nerve)
↓
Effector (The hand will move up by muscles contraction)
↓
Response (open the door)

1. The Meninges are three protective membrane layers surrounding the Brain and spinal cord.
2. CSF occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord.

Gibberellins break dormancy in seeds and produce an elongation of the stem by increasing the length of the internodes.

The different refractive mediums of the eyeball are:Aqueous chamber (Aqueous humour) → Lens → Vitreous Humour.

During Meiosis cell division, the significance of the following two phenomena are:

1. Reduction in the number of chromosomes: The chromatids of each chromosome get separated. Therefore, in meiosis, the final product gets half the number of chromosomes of the mother cell. This led to the formation of gametes.
2. Exchange of segment between chromatids: Exchange in the segment between two chromatids gives birth to new variations in the offspring.

Feature	Asexual	Sexual
Number of patents	Only one parent is required.	Two parents are required.
Nature of offspring	The offspring are genetically identical to the parent.	The offspring are not genetically identical to the parents.

1. Metaphase
2. Anaphase
3. Prophase
4. Anaphase

Here are two characters having opposite traits that Mendel selected to establish the law of segregation in pea plants:

• Flower colour: Purple and white
• Seed shape: Round and wrinkled

X°X – Carrier woman.

X°Y – Colour blind man.

Result – 50% of daughters colour blind

50% daughter carrier.

Conclusion – The born female baby may be colourblind or carrier possibly – 50% checkerboard.

Colour blindness and Haemophilia are the two genetic diseases expressed in the human population.

Interspecific and Intraspecific struggle.

The following are the two adaptations in the Sundari plant for tolerance of salt:

1. Sundari plants possess succulent leaves and stem.
2. They possess thick-walled cutinized epidermis with hairy covering.

Chimpanzees are quite clever and can prepare a tool with a small tree branch. After defoliating the tip of the twig, it is crushed to prepare it like a brush. Then the brush is inserted into the termite mound. This stick-like brush is then pulled out when quite a good number of termites may be collected for eating.

1. Greenhouse gas: Causes global warming, climate change, and sea-level rise.
2. SPM (Suspended Particulate Matter): Leads to respiratory problems, heart disease, and air pollution.
3. Chemical fertilizers: Causes soil degradation, water pollution (eutrophication), and loss of biodiversity.
4. Non-biodegradable chemical insecticide: Accumulates in the food chain (bioaccumulation), harms wildlife, and contaminates soil and water.

(i) European gipsy math, (ii) European starting

(i) Zebra Musscle (ii) Chinese Mittuch crab

The crocodile reserve project was started.The Bhagabatpur Crocodile Reserve project is situated in West Bengal to conserve crocodiles.

(i) Food (ii) Skin (iii) Horns (iv) Ivory etc

The diagram of the anaphase

1. Dendrites: Receive electrical signals from other neurons.
2. Cell body: Contains the nucleus and other organelles.
3. Axon: Transmits electrical signals to other neurons.
4. Myelin sheath: Insulates the axon and speeds up the signal transmission.
5. Schwann cells: Produce the myelin sheath.

Here are three changes that occur in the anaphase stage of mitosis in animal cells:

1. The sister chromatids separate and move to opposite poles of the cell. This is caused by the breakdown of the cohesin proteins that hold the sister chromatids together.
2. The spindle fibres shorten, pulling the chromosomes apart. This is caused by the activity of the motor proteins on the spindle fibres.
3. The nuclear envelope reforms around each set of chromosomes. This is caused by the assembly of new nuclear membranes around the chromosomes.

Here are the names of two structural parts of the eukaryotic chromosome:

1. Centromere: The centromere is the region of the chromosome where the sister chromatids are attached.
2. Telomere: The telomere is the end of the chromosome. It is a repetitive sequence of DNA that protects the chromosome from damage.

Here are some reasons why reproduction is important for an organism:

1. Reproduction ensures the continuity of the species
2. Reproduction allows for genetic variation
3. Reproduction can be a source of pleasure

Meiosis is characteristically different from mitosis in the following ways:

1. Meiosis produces haploid cells, while mitosis produces diploid cells.
2. Meiosis involves two rounds of cell division, while mitosis only involves one round.
3. Meiosis is involved in sexual reproduction, while mitosis is involved in asexual reproduction.

Here are five processes of asexual reproduction with one suitable example for each:

1. Binary fission: A single cell divides into two identical cells. This is the most common form of asexual reproduction and is found in bacteria, amoebas, and many other organisms. [Example: E. coli bacteria reproduce by binary fission.]
2. Budding: A small outgrowth, or bud, develops on the parent cell and eventually separates to form a new organism. This type of reproduction is found in yeast, hydras, and some plants. [Example: Yeast reproduce by budding.]
3. Fragmentation: The parent organism breaks into multiple pieces, each of which can develop into a new organism. This type of reproduction is found in many marine organisms, such as sea stars and planarians. [Example: Planarians reproduce by fragmentation.]
4. Spore formation: The parent organism produces spores, which are small, reproductive units that can develop into new organisms. This type of reproduction is found in fungi, algae, and some plants. [Example: Molds reproduce by spore formation.]
5. Vegetative propagation: New plants are produced from parts of the parent plant, such as stems, leaves, or roots. This type of reproduction is found in many plants, such as strawberries, potatoes, and cacti. [Example: Strawberries reproduce by vegetative propagation.]

F2 Phenotypes:

• Black, Coarse-haired (BBRR, BBRr, BbRR, BbRr): 9/16
• Black, Smooth-haired (BBrr, Bbrr): 3/16
• White, Coarse-haired (bbRR, bbRr): 3/16
• White, Smooth-haired (bbrr): 1/16

Conclusion:

The hybridization experiment shows that black color (B) and coarse hair (R) are dominant traits, while white color (b) and smooth hair (r) are recessive traits. The F2 generation exhibits a typical 9:3:3:1 ratio of phenotypes, illustrating Mendel’s law of independent assortment.

Symptoms expressed in a child affected with Thalassae:

1. Less formation of Hemoglobin
2. Anaemia
3. Excessive deposition of iron
4. Unusual formation of bones
5. Stunted growth
6. Cardiac problems.

Suggestions to be given at the time of genetic counselling in case of Thalassaemia.

• Carrier couples should not take any child.
• To undergo proper blood lest prior to pregnancy.
• They should be aware of the possible complications of the baby.

Here is a brief outline of the chemical origin of life mentioning Miller and Urey’s experiment:

• The chemical origin of life is the study of how life on Earth first arose from non-living matter.
• The Miller-Urey experiment simulated the conditions of the early Earth and showed that organic molecules could form from non-living matter.
• These organic molecules could have been the building blocks of the first living cells.
• There is still much that we do not know about the chemical origin of life, but the Miller-Urey experiment was a major step forward in our understanding.

Here are two major tenets of Lamarck’s evolutionary theory:

• Use and disuse: Lamarck believed that organisms could change over time in response to their environment. If an organism used an organ more, it would become stronger and larger. If an organism did not use an organ, it would become weaker and smaller.
• Inheritance of acquired characteristics: Lamarck also believed that these acquired characteristics could be passed on to offspring. For example, if a giraffe’s neck became longer because it was constantly reaching for leaves, its offspring would also have longer necks.

Here are the roles of bacteria in three steps of the nitrogen cycle:Nitrogen fixation: Bacteria are responsible for converting atmospheric nitrogen gas (N₂) into forms that plants can use, such as ammonia (NH₃). This process is called nitrogen fixation.

• Free-living bacteria: Some bacteria, such as Azotobacter and Clostridium, can fix nitrogen in the soil.
• Symbiotic bacteria: Other bacteria, such as Rhizobium, form symbiotic relationships with plants. These bacteria live in nodules on the roots of legumes, such as peas and beans.

Nitrification: Bacteria convert ammonia into nitrites (NO₂^–) and then into nitrates (NO₃^–). This process is called nitrification.

• Nitrosomonas: Bacteria in the genus Nitrosomonas convert ammonia into nitrites.
• Nitrobacter: Bacteria in the genus Nitrobacter convert nitrites into nitrates.

Denitrification: Bacteria convert nitrates back into nitrogen gas. This process is called denitrification.

• Pseudomonas: Bacteria in the genus Pseudomonas can denitrify.
• Thiobacillus denitrificans: Bacteria in the genus Thiobacillus can denitrify.

A luxurious and comfortable lifestyle is one of the major reasons for air pollution. This is because many of the activities that we associate with a luxurious and comfortable lifestyle, such as driving cars, using air conditioners, and burning fossil fuels, produce air pollutants.

Two examples of animal biodiversity endangered by the pollution of the river Ganga

1. Gangetic dolphin
2. Gharial

Here are three incidences which occurred as a result of the disruption of the nitrogen cycle:

• Algal blooms: When the nitrogen cycle is disrupted, it can lead to algal blooms. These are large growths of algae that can occur in water bodies. Algal blooms can be harmful to aquatic life and can also produce toxins that can be harmful to humans.
• Eutrophication: Eutrophication is a process by which water bodies become enriched with nutrients. This can lead to the growth of algae and other aquatic plants, which can eventually deplete the oxygen levels in the water, leading to the death of fish and other aquatic life.
• Nitrate contamination: Nitrates are a form of nitrogen that can be found in groundwater and surface water. When nitrates are present at high levels, they can be harmful to human health. Nitrates can also contribute to the formation of smog.

Due to anthropogenic activity, these are pollution, deforestation and other degradation in the environment. These changes in atmospheric conditions, cause natural changes and global warming. Greenhouse gases are increased. Melting of ice and rise of sea level are occurring. Loss of biodiversity, acid rain, heavy rainfall etc. are other impacts on the environment due to changes in climate and global warming resulting from the increasing human population.(i) Asthma:

Symptoms can include wheezing, shortness of breath, chest tightness, and coughing.

(ii) Bronchitis-

Symptoms include a productive cough (coughing up mucus), wheezing, shortness of breath, and chest pain.

OR

You have identified three environmental problems while on research in Sunderbans －

1. Disbalance in prey-predator number.
2. Destruction of mangrove plants due to urbanization.
3. Submergence of islands due to rising sea level

Disbalance in prey-predator number – The shrinking of mangrove vegetation has resulted in a reduction in the number of herbivores and as a result of which they carni- vores are becoming endangered in this case the number of tigers is going down and moreover they are getting killed. Gradually the ecosystem will be unbalanced.Destruction of Mangrove plants due to urbanization- Due to urbanization the mangrove plants are destroyed. The destruction of the Mangrove forest and the progressing human settlement have resulted in the loss of habitat for the animals, making them endangered and vulnerable. As a result, they may become extinct in future.

Submergence of Islands Due to rising sea level:-

An increased number of islands are getting submerged due to increasing water levels as a result of which the habitat is getting shrunk and that has reduced the habitat. In want of habitat and food the species of various tropic levels will be lost.

Location of Sundaland hotspot:- It is a biogeographical region of South Eastern Asia.

Important species:- Elephant