1. Name the modification to which runner, stolon and sucker belong.
(A) Underground modification of stem.
(B) Sub-aerial modification of stem.
(C) Modification of leaves.
(D) Aerial modification of stem.
2. Choose an organism which transmits Malaria in humans:
(A) Female Culex mosquito
(B) Aedes mosquito
(C) Plasmodium
(D) Female Anopheles
3. From which part of the plant does guttation take place?
(A) Lenticels
(B) Cuticle
(C) Stomata
(D) Hydathodes
4. __________ is an autosomal disorder.
(A) Down’s syndrome
(B) Turner’s syndrome
(C) Sickle cell anaemia
(D) Haemophilia
5. Animals with soft, unsegmented body protected by a calcareous shell and a muscular foot for locomotion belong to which group?
(A) Arthropoda
(B) Echinodermata
(C) Mollusca
(D) Amphibia
6. Priya is unable to see in dim light. Lack of which nutrient is she suffering from?
(A) Protein
(B) Vitamin A
(C) Vitamin C
(D) Vitamin B
7. Parthenocarpy is:
(A) Production of seeds with pollination and fertilisation
(B) A type of asexual reproduction
(C) Development of plants by micropropagation
(D) Development of fruit from unfertilized ovary
8. Bt. crops are:
(A) Transgenic crops
(B) Hybrid crops
(C) Crops which are pest-resistant
(D) Crops on which Bacillus thuringiensis forms gall
2 MARKS QUESTIONS
9. Draw a neat and labelled diagram of a stomatal apparatus of a dicot leaf.
Ans:
10. (a) List any two adaptations found in Entomophilous flowers.
(b) List any two adaptations to promote cross-pollination in flowers.
Ans:
11. Briefly explain double fertilisation in Angiosperms.
Ans: One sperm fuses with the egg (syngamy) and forms a diploid zygote. The other sperm fuses with the secondary nucleus to form the primary endosperm nucleus, which is triploid in nature. Since two types of fusion, syngamy and triple fusion, take place in an embryo sac, the process is termed double fertilisation.
12. Distinguish between chondrichthyes and osteichthyes with suitable examples.
Ans:
Chondrichthyes
Osteichthyes
mouth ventral
Mouth terminal
tail heterocercal
Tail homocercal
Skeleton cartilaginous
Skeleton bony
Five to seven pairs of gills
Four pairs of gills
Operculum (gill cover) absent
Operculum present
Example: Scoliodon (dog-fish)
Example: Labeo (Rohu)
13. (a) Give an example each of broad-spectrum antibiotics and narrow spectrum antibiotics.
(b) State any two drawbacks of using antibiotics.
Ans: a)
Broad-spectrum antibiotic: Chloramphenicol
Narrow-spectrum antibiotic: Penicillin
b) Drawbacks of using antibiotics
Some people are allergic to a particular antibiotic.
Some disease-causing bacteria undergo mutation and become resistant to a particular antibiotic to which they were sensitive earlier.
14. Distinguish between in situ and ex situ conservation of Biodiversity.
Ans:
In situ (on-site conservation includes the protection of plants and animals within their natural habitats or in protected areas. Protected areas are areas of land or sea dedicated to the protection and maintenance of biodiversity. For example: e.g., National Parks, Wildlife Sanctuaries, Biosphere Reserves, etc.
Ex-situ (off-site) conservation is the conservation of plants and animals outside their natural habitats. These include Botanical Gardens, Zoo, Gene Banks, DNA Banks, Seed Banks, Pollen Banks, Seedling and Tissue Culture, etc.
15. Mention any four activities which help in maintaining sustainable development.
Ans:
Reducing excessive use of resources and enhancing resource conservation.
Recycling and reuse of waste materials.
Scientific management of renewable resources, especially bio-resources.
Planting more trees.
Green grassy patches are to be interspersed between concrete buildings.
Using more environmentally friendly materials or biodegradable materials.
Use of technologies which are environmentally friendly and based on efficient use of resources.
16. State the four characteristics of the muscle fibres.
Ans: The muscle fibres have the following characteristics:
Excitability (respond to stimulus)
Extensibility (stretch)
Contractility (contract)
Elasticity (move back to the original position)
17. Draw a neat and labelled diagram of Chlamydomonas.
Ans:
18. Define the following terms:
(a) Ecotone
(b) Ecological succession
Ans:
An ecotone is a transitional zone between two ecosystems.
The process by which communities of plant and animal species in an area are replaced by another over a period of time is known as ecological succession.
19. Name any two disorders of the musculoskeletal system which are hereditary.
Ans:
Myasthenia gravis is caused by a gene on the X chromosome and so is hereditary. The muscles slowly waste away, and the patient gradually becomes immobile, and in the last stages, even the jaw muscles do not work, and the patient is unable to eat.
Muscular dystrophy is an autosomal dominant disorder. In this hereditary disorder, muscles waste away, and the person becomes immobile.
20. (a) Name a naturally occurring growth inhibitor found in a wide variety of plants.
(b) Define the term Vernalisation.
Ans:
Abscisic acid
Low temperature treatment, which stimulates early flower formation in some plants, is called vernalisation.
4 MARKS QUESTIONS
21. List any four criteria for essentiality of elements for a healthy growth of plants.
Ans:
An essential element is absolutely necessary for normal growth and reproduction of the plant, and should be a part of the essential metabolites for plant growth.
The requirement of the element is very specific, and it cannot be replaced by another element.
The element is directly or indirectly involved in the metabolism of a plant.
In the deficiency of an essential element, the plant would exhibit specific symptoms of deficiency, and the plant would recover from its symptoms if supplied with the deficient element.
22. How do Archaebacteria differ from Eubacteria? State the three types of Archaebacteria and also mention the location they are found.
Ans: Archaebacteria include bacteria that live in unusual environments, particularly at low levels of oxygen. Eubacteria include all other bacteria, excluding cyanobacteria.
The main types of Archaebacteria are
Methanogenic bacteria that live in sewage and the intestinal tracts of animals
Thermoacidophilic bacteria that live in hot springs.
Halophilic bacteria live in salty conditions where the hot sun concentrates seawater.
23. A high population growth has severe environmental implications. List any four effects of such uncontrolled population growth on our country.
Ans:
Increasing population and transportation: An Increase in population requires a corresponding increase in the means of transport. An increase in the number of automobiles as a consequence of phenomenal population growth has increased the pollution load (air pollution, water pollution and solid waste pollution).
Increasing population and education: Education is most important for economic and social upliftment. Although the literacy rate is growing, we still have a very large number of illiterates in the country. The increasing population further adds to the problems of providing education to all.
Increasing population, agricultural development and environmental degradation: In order to meet the food requirements of the ever-increasing population of the country, new agricultural techniques have been adopted. Some of these have proved to be detrimental to the environment.
Increasing population and water: The availability of water is limited. The increasing population needs more water for drinking, bathing, washing, etc. Thus,the availability of water is becoming scarce.
24. (a) Draw a neat diagram of the double helical structure of DNA.
(b) Who proposed this structure?
Ans:
Double helical structure of DNA
Franklin and Wilkins
25. (a) Draw a neat and labelled diagrammatic structure of an Antibody.
(b) Distinguish between an antigen and an antibody.
Ans:
Antibody
An antigen is any foreign molecule that can trigger a specific immune response. An antibody is a protein molecule produced in animals in response to an antigen.
26. (a) Draw a neat diagram of the Excretory organs in humans and label the following parts:
Kidney, Ureter and Urethra
(b) Name the structural and functional units of the kidney.
Ans:
Excretory organs in humans
Structural and functional unit of the kidney: Nephrons
6 MARKS QUESTIONS
27. (a) Draw a neat and labelled diagram of the internal structure of the human ear.
(b) Briefly explain the mechanism of hearing.
Ans:
Human ear
Mechanism of hearing
The sound waves enter the auditory canal and cause the eardrum to vibrate.
The vibrations of the eardrum are transferred to the malleus, to the incus, and then to the stapes. Stapes transfers the vibrations through the oval window into the cochlea.
These vibrations move the fluid in the cochlea. The organ of Corti catches the movement of the fluid and transfers it to the auditory nerve that carries the impulses to the brain.
28. Briefly state two contrasting features each in sex-determination in humans, birds and in
honey bees?
Ans:
Sex determination in humans
In humans, males are heterogametic and females are homogametic
Males produce XY sex chromosomes while females produce XX.
Sex determination in birds
In birds, females are heteromorphic and males are homomorphic.
Females produce A+Z and A+W gametes. Males produce only A+Z gametes.
Sex determination in honey bees
Fertilised eggs produce females, and unfertilised eggs become males.
Females are diploid and males are haploid.
29. (a) Give the generalised balanced equation to show the process of Photosynthesis.
(b) Expand the abbreviations:
(i) Rubisco and
(ii) PEPco and explain the role of these enzymes. Where are these enzymes present in the C4 plants?
(c) What do you understand by Compensation point?
Ans:
Photosynthesis
Expand:
Rubisco: Ribulose Bisphosphate Carboxylase/oxygenase. Rubisco is a part of the C3 cycle and combines with CO2 to produce a C3 compound called PGA.
PEPco: PEP carboxylase. PEPCo is a part of the C4 pathway and combines with CO2 to form a C4 compound called OAA.
c) At a certain light intensity, the amount of CO2 used in photosynthesis and the amount of CO2 produced in respiration are the same. This point of light intensity is known as the compensation point.
30. (a) List any four functions of fat in our diet.
(b) What is the special balanced diet required by a woman during her pregnancy?
(c) (i) List any two causes of obesity.
(ii) List two effects of obesity on the person.
Ans:
Functions of fats
Fats are the richest sources of energy. On biological oxidation, one gram of fat provides 37 kJ of energy.
Form structural components of the cell cytoplasm and cell membrane.
Help in absorption of fat-soluble vitamins A, D, E and K
It acts as a precursor of various hormones.
It can be stored for subsequent use by the body.
Subcutaneous fats serve as an insulator in the body, thus protecting it from cold weather and pressure.
Stored fat provides padding to protect the vital organs of the body from shocks.
Helps in the synthesis of vitamin D and steroid hormones in the body.
The pregnant women and lactating mothers should take,
Extra protein for tissue growth
More calcium and phosphorus are needed to form bones of the baby
More iron is needed to make sufficient blood for the baby
More carbohydrates for herself because extra energy is required to carry out all the building processes linked with the embryo.