CBSE Class 6 Science Advanced Biology Getting to Know Plants MCQs Set 01

Answer: (b) Trunk

Explanation:
1. A tree has one thick, hard stem that carries the branches, twigs and leaves.
2. This main woody stem is called the trunk, and it is covered by bark.

Teacher's Note:
1. A node is only the point where a leaf joins the stem.
2. Remember: trunk = tree stem.

Answer: (a) Coconut

Explanation:
1. Apple and mango trees have many branches that spread from the trunk.
2. Coconut (like palm) has a single unbranched trunk with a crown of leaves at the top.
3. So the answer is coconut.

Teacher's Note:
1. The book names coconut and palm as trees without branches.
2. Think of a palm: one pole and leaves only on top.

Answer: (c) Carrot

Explanation:
1. Onion stores food in its leaves, which form a bulb (a modified stem).
2. Balsam and zinnia do not have storage roots.
3. Carrot has a swollen taproot full of stored food: carrot.

Teacher's Note:
1. Root storage examples: carrot, radish, turnip, beetroot.
2. Do not choose onion, because its storage part is a bulb.

Answer: (a) Stems

Explanation:
1. Food is made in the leaves.
2. The stem carries this food, along with water and minerals, to all other parts.
3. So the part that conducts food is the stem.

Teacher's Note:
1. Leaves make food; stems carry it.
2. Roots take in water and minerals from the soil.

Answer: (d) Pea

Explanation:
1. Wheat, rice and maize are monocots and have fibrous roots.
2. Pea is a dicot, and dicots have a taproot: pea.

Teacher's Note:
1. Monocot = fibrous roots; dicot = tap root.
2. Grasses and cereals are monocots.

Answer: (b) Leaf

Explanation:
1. Photosynthesis needs chlorophyll, sunlight, water and carbon dioxide.
2. The leaf has plenty of chlorophyll and stomata, so food is made there: leaf.

Teacher's Note:
1. The leaf is called the food factory of the plant.
2. Green stems of cacti also photosynthesise, but the leaf is the usual answer.

Answer: (c) Rose

Explanation:
1. Wheat, maize and rice are monocots; their leaves have parallel venation.
2. Rose is a dicot, and its leaves show a net-like (reticulate) pattern: rose.

Teacher's Note:
1. Net-like veins go with a taproot; parallel veins go with fibrous roots.
2. Mango and pea leaves are also reticulate.

Answer: (b) Sepals

Explanation:
1. The outermost whorl of a flower is the calyx, made of green leaf-like sepals.
2. Petals are coloured, and stamens and anthers are male parts.
3. So the answer is sepals.

Teacher's Note:
1. Sepals protect the flower when it is a bud.
2. Calyx = sepals; corolla = petals.

Answer: (b) Stamen

Explanation:
1. The pistil and ovule are female parts.
2. A pollen grain is only a cell produced inside the male organ.
3. The male reproductive organ is the stamen.

Teacher's Note:
1. Stamen = anther + filament.
2. Together, stamens make the androecium.

Answer: (b) Pistils

Explanation:
1. Stamens are male parts, and petals and sepals are non-reproductive.
2. The female part (gynoecium) is made of pistils.

Teacher's Note:
1. Pistil = stigma + style + ovary.
2. The ovary holds the ovules.

Answer: (c) Ovary

Explanation:
1. After fertilization the ovary grows and becomes the fruit.
2. The ovules inside it turn into seeds.
3. So the answer is ovary.

Teacher's Note:
1. Ovary becomes fruit; ovule becomes seed.
2. Sepals and petals usually wither.

Answer: (d) Rubber

Explanation:
1. Sugarcane and maize have stilt roots from their lower nodes.
2. Rice has ordinary fibrous roots.
3. Prop roots grow down from horizontal branches in banyan and the rubber tree: rubber.

Teacher's Note:
1. Stilt roots come from stem nodes; prop roots come from branches.
2. Banyan is the standard example of prop roots.

Answer: (d) Mangroves

Explanation:
1. Mangrove plants grow in marshy, salty soil that has little air.
2. They send up special roots (pneumatophores) for gaseous exchange.
3. So the answer is mangroves.

Teacher's Note:
1. Breathing roots = pneumatophores.
2. They stick out of the muddy water.

Answer: (b) Dodder

Explanation:
1. Dodder has no roots of its own in the soil and sucks water and food from its host.
2. It does this with special roots, so it has parasitic roots.

Teacher's Note:
1. Dodder (amarbel) is a yellow, leafless climber on other plants.
2. Radish stores food, and banyan has prop roots.

Answer: (b) Turnip

Explanation:
1. Nodes and internodes are found on stems.
2. Ginger is a stem (rhizome), rose and palm have stems.
3. Turnip is a swollen root, and roots have no nodes or internodes: turnip.

Teacher's Note:
1. Roots lack nodes; stems have them.
2. Ginger looks like a root but is an underground stem.

Answer: (b) Stomata

Explanation:
1. Leaves have tiny pores for gas exchange and for letting out water vapour.
2. These pores are stomata.

Teacher's Note:
1. Lenticels are the pores on woody stems.
2. Stomata are found mostly on the lower leaf surface.

Answer: (c) Cacti

Explanation:
1. In cacti the leaves become spines, and the stem turns green and flat.
2. This green stem makes food by photosynthesis, doing the leaf's work: cacti.

Teacher's Note:
1. Spines cut down water loss.
2. The green stem of a cactus is called a phylloclade.

Answer: (a) pollen grains

Explanation:
1. The anther is the top part of the stamen.
2. Its pollen sacs are filled with tiny pollen grains.

Teacher's Note:
1. Ovules and ovary belong to the pistil.
2. Pollen looks like yellow dust.

Answer: (c) Pollination

Explanation:
1. Moving pollen from an anther to a stigma is called pollination.
2. Fertilization is the later joining of male and female gametes, and germination is the sprouting of a seed.

Teacher's Note:
1. Pollination comes first, fertilization afterwards.
2. Insects, wind and water carry pollen.

Answer: (a) Potato

Explanation:
1. Carrot, beetroot and turnip are modified taproots.
2. Potato is a tuber, which is a swollen underground stem with buds (eyes): potato.

Teacher's Note:
1. Potato eyes are buds, a stem feature.
2. Roots never carry buds in this way.

Answer: (c) Paddy

Explanation:
1. The figure shows a cluster of thin, equal roots spreading from the base of the stem, a fibrous root system.
2. Marigold, mango and balsam are dicots with taproots.
3. Paddy is a monocot with fibrous roots: paddy.

Teacher's Note:
1. Fibrous roots go with monocots such as rice (paddy).
2. No single thick main root is visible in the figure.

Answer: (b) Q

Explanation:
1. P shows sunlight falling on the leaf, and S shows water being taken from the soil.
2. During photosynthesis the leaf takes in carbon dioxide and gives out oxygen.
3. The arrow marking this release of oxygen from the leaf is Q.

Teacher's Note:
1. Arrow R shows carbon dioxide entering the leaf.
2. Oxygen leaves the leaf through the stomata.

Answer: (a) Oxygen

Explanation:
1. A water plant kept in sunlight carries out photosynthesis.
2. Photosynthesis gives out oxygen, which rises as bubbles and collects at the top of the inverted test tube.
3. So the gas is oxygen.

Teacher's Note:
1. Water plants such as Hydrilla are used for this experiment.
2. A glowing splinter relights in the collected gas.

Answer: (b) (b) - (i) Stamen, (c) - (i) Petals, (ii) Pollination

Explanation:
1. (a) In cacti the stem, not the root, is thick, fleshy and green, so every option with 'Root' for (a) is wrong.
2. (b) The male part is the stamen, and (c) coloured petals attract insects for pollination.
3. Only option (b) has correct entries for both statements it fills: (b).

Teacher's Note:
1. Eliminate options that put 'Root' in (a).
2. Coloured parts of a flower are the petals, not the sepals.

Answer: (c) Herbs: Plants with hard stem, not very thick; Shrubs: Plants with green and tender stems; Trees: Plants with thick brown stem

Explanation:
1. Option (a) lists correct examples and (b) correct sizes.
2. In (d) herbs have few branches, shrubs branch near the base and trees branch higher up, which is correct.
3. In (c) the stems are swapped: herbs have soft, green, tender stems and shrubs have hard woody stems. So (c) is incorrect.

Teacher's Note:
1. The question asks for the incorrect statement.
2. Remember: herbs soft, shrubs woody, trees thick and woody.

Answer: (d) All of these

Explanation:
1. The coloured water moved up into the petals, so the stem conducts water to the flower (A).
2. Red and blue stayed in separate areas of the stem section, so the stem has separate conducting channels (B).
3. The dyes were dissolved in the water and travelled with it, so solutes are conducted with water (C).
4. All three conclusions are right: All of these.

Teacher's Note:
1. The same idea is used in the red-ink and balsam activity.
2. When every statement is true, choose 'All of these'.

Answer: (b) (i), (iii), (v) and (vi)

Explanation:
1. Reading the figure: P is the stigma, Q the anther, V the style, S the ovary, R the ovule, T the petals and U the sepals.
2. (i) true: the ovary becomes the fruit and the ovule the seed. (ii) false: pollen is in the anther Q, not in the stigma P. (iii) true: pollen moves from anther Q to stigma P. (iv) false: U is a sepal, and it is the petals that attract insects. (v) true: petals differ in colour. (vi) true: stigma, style and ovary make the pistil.
3. Correct statements are (i), (iii), (v) and (vi): option (b).

Teacher's Note:
1. First name every labelled part, then test each statement.
2. Stigma, style and ovary together are the pistil.

Answer: (d) Leaves of P and Q show parallel venation, while that of R shows reticulate venation

Explanation:
1. P is a banana plant, Q is wheat and R is a grapevine; all three are green plants, so all make food and release oxygen. This rules out (a) and (b).
2. P is a tall herb and Q is a herb, while R is a climber, not a tree, so (c) is wrong.
3. Banana and wheat are monocots with parallel venation, and grape is a dicot with net-like (reticulate) venation: (d).

Teacher's Note:
1. Every green plant photosynthesises.
2. Grapevine has tendrils, so it is a climber.

Answer: (d) Norman Ernest Borlaug

Explanation:
1. Verghese Kurien led the White Revolution (milk).
2. Hilaire de Chardonnet is known for artificial silk, and Norman de Kazimodke is not a known scientist.
3. The Nobel Peace Prize of 1970 for high-yielding wheat went to Norman Ernest Borlaug.

Teacher's Note:
1. Green Revolution = more food grains, especially wheat and rice.
2. In India it is linked to M. S. Swaminathan as well.

Answer: (b) Photosynthesis does not occur in these plants as they depend only upon insects for their food

Explanation:
1. The passage says the plants have green leaves, so they photosynthesise and make carbohydrates, as in (a) and (d).
2. Insects supply nitrogen (c), not the main food.
3. Statement (b) says photosynthesis does not occur, which is false: (b) is incorrect.

Teacher's Note:
1. The question asks which statement is incorrect.
2. Insects are a source of nitrogen, not of all food.

Answer: (a) Pot P: Plant covered within netted container without insects; Pot Q: Plant covered within netted container with insects

Explanation:
1. To show that the plant makes its own food, one pot must keep insects away and be compared with a pot that has insects.
2. If the starch test is positive in leaves of the pot without insects, the plant must have made starch by photosynthesis.
3. Only set (a) changes just this one factor: (a).

Teacher's Note:
1. A good experiment changes only one thing.
2. Positive starch test with no insects means food was made by the plant.

Answer: (d) S - Ovary - Involved in fertilization

Explanation:
1. From the figure: P is the stigma, Q is the anther, R is the style and S is the ovary.
2. In (a) P is not the anther, in (b) Q is not the stigma, and in (c) the style does not transfer the ovule.
3. Option (d) is right: the ovary holds the ovule, where fertilization takes place: (d).

Teacher's Note:
1. Name the labelled parts first.
2. Fertilization happens inside the ovary, in the ovule.

Answer: (d) Both (A) and (C)

Explanation:
1. Desert plants must save water.
2. Leaf hairs and needle-like leaves both reduce water loss, while large flat leaves would lose a lot of water.
3. So both (A) and (C) are useful: (d).

Teacher's Note:
1. A cactus has spines in place of leaves.
2. Small leaf area means less transpiration.

Answer: (c) Ginger and cactus

Explanation:
1. Ginger is an underground stem (rhizome) that stores food.
2. A cactus stem is green and makes food.
3. So X is ginger and Y is cactus: (c).
4. Sweet potato and dahlia are roots; onion is a bulb and potato a tuber, but neither pair has a food-making stem.

Teacher's Note:
1. Sweet potato and dahlia store food in roots.
2. Cactus is the standard example of a food-making stem.

Answer: (d) X: Opposite; Y: Alternate; Z: Whorled

Explanation:
1. In X two leaves arise at each node on opposite sides, which is opposite phyllotaxy.
2. In Y one leaf arises at each node and the leaves are on alternate sides, which is alternate phyllotaxy.
3. In Z several leaves arise together around one node, which is whorled phyllotaxy.
4. So X, Y, Z = Opposite, Alternate, Whorled: (d).

Teacher's Note:
1. Count the leaves at a single node: one means alternate, two means opposite, more than two means whorled.
2. Guava has opposite leaves, china rose alternate, and Alstonia whorled.