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Solutions for Biology, Class 8, ICSE
Discuss the ascent of sap with the help of a neatly labelled diagram.
Ascent of sap in plants is described below:
Name the four blood groups in human beings. On what basis are they named?
The four blood groups in human beings are A, B, AB and O. They are named on the presence or absence of specific antigens.
Name several types of vegetative propagation in flowering plants with an example of each kind.
Vegetative reproduction in plants are of two types. They are:
Write about the different parts of the female reproductive system of human beings.
The reproductive system in females consists of a pair of ovaries, the fallopian tubes or oviducts and the uterus. The ovaries are almond-sized oval glands situated in the pelvic or hip region. They produce the eggs or ova. The mature egg moves through funnel-shaped muscular tubes called fallopian tubes or oviducts towards the uterus. The uterus lies in the lower abdomen behind and above the urinary bladder. The uterus is a hollow, muscular pear-shaped organ. It is in the uterus that the zygote develops into a baby. The lower part of the uterus is called cervix. The cervix is narrow and opens to the outside through a muscular tube called the vagina. The vagina receives the sperms. It also serves as the birth canal through which the mature baby is delivered.
Explain the flow of energy in a food chain with the help of a diagram.
Green plants convert solar energy into chemical energy present in food. Some energy gets stored in plants while the rest is used up by them. When the plants are eaten by herbivores, the energy stored in them is transferred to herbivores. Herbivores use some of the energy for their activities and store a part of it in their body. This stored energy is further transferred to carnivores when they eat herbivores. Thus, as one organism eats the other, energy passes on from producers to herbivores and then to carnivores. The given diagram shows the flow of energy in a food chain:
Osmosis and diffusion
| Sl. No. | Osmosis | Diffusion |
|---|---|---|
| 1. | The movement of water molecules through a semi-permeable membrane from an area of its higher concentration to an area of its lower concentration is called Osmosis. | The movement of salt or mineral molecules from a region of their higher concentration to a region of their lower concentration is called Diffusion. |
| 2. | It takes place only in a liquid medium. | It takes place in any medium such as solid, liquid and gas. |
| 3. | It requires a semi-permeable membrane. | It does not require any semi-permeable membrane. |
| 4. | It is a slow process. | It is comparatively a faster process in gases, slow in liquids. |
Diffusion and active transport
| Sl. No. | Diffusion | Active transport |
|---|---|---|
| 1. | It is the movement of molecules or ions of a substance from a region of their higher concentration to a region of their lower concentration. | It is the movement of ions of a substance from their lower concentration region to their higher concentration region using energy. |
| 2. | It is the movement of solute or solvent molecules. | It is the movement of ions only (no water). |
| 3. | No cell energy is needed. | Cell energy is needed in the form of ATP. |
| 4. | It occurs through a non-living permeable membrane. | It occurs through a living selectively permeable membrane. |
Auricles and Ventricles
| Sl. No. | Auricles | Ventricles |
|---|---|---|
| 1. | Upper two chambers of heart are called Auricles. | Lower chambers of heart are called ventricles. |
| 2. | They have thinner walls than ventricles. | They have thick walls. |
| 3. | They receive blood from different part of the body. | They pump blood out of heart. |
Cutting and Grafting
| Sl. No. | Cutting | Grafting |
|---|---|---|
| 1. | In this method, a part of stem with an axillary bud is cut and planted in moist soil. | In this method, a stem cutting (scion) from one plant is attached and tied to the rooted stem (stock) of another plant. |
| 2. | New plant is identical to parent plant. | The plant is superior than both the parent plants. |
| 3. | Cutting is used in propagation of Rose, Cacti, Bougainvillea etc. | Grafting is used in Rose, Mango, Guava etc. |
Ovaries and Testes
| Sl. No. | Ovary | Testes |
|---|---|---|
| 1. | Ovaries are part of the female reproductive system. | Testes are part of the male reproductive system. |
| 2. | The ovaries are situated in the pelvic or hip region. | Testes are located outside the abdomen in a sac-like structure called scrotum. |
| 3. | Eggs (ova) are produced and released by ovaries. | Sperms are produced in testes. |
Food chain and Food web
| Sl. No. | Food chain | Food web |
|---|---|---|
| 1. | A series of organisms that are linked to each other through a process of eating and being eaten form a food chain. | Several food chains are interconnected to form a food web. |
| 2. | It is basic chain showing flow of energy. | It is a complex network showing flow of energy at different trophic levels in different food chains. |
The force with which sap is pulled up by plants is called ............... .
The force with which sap is pulled up by plants is called transpiration pull.
Blood group AB has ............... and antibodies ............... .
Blood group AB has both antigens and antibodies are absent.
A mass of unorganized cells growing in a nutrient medium is called ............... .
A mass of unorganized cells growing in a nutrient medium is called callus.
A ............... is formed as a result of fertilization.
A zygote is formed as a result of fertilization.
Fertilization takes place in the fallopian tubes or ............... .
Fertilization takes place in the fallopian tubes or oviduct.
Living organisms that cannot make their own food but consume either plants or other animals, are called consumers or ............... .
Living organisms that cannot make their own food but consume either plants or other animals, are called consumers or heterotrophs .
............... are also called nature's scavengers.
Decomposers are also called nature's scavengers.
Mineral solutes do not pass on from the roots into the soil but water is drawn into the roots from the soil.
Mineral molecules are more concentrated inside the root hair cells than in the soil outside. Still, mineral solutes do not pass on from the roots into the soil but water is drawn into the roots from the soil. It is because plants use the process of active transport and absorb against the gradient at expense of energy. The movement of minerals ions from a region of their lower concentration to a region of their higher concentration is called active transport. This process involves the use of energy (ATP).
White blood cells are described as the 'soldiers' of the body.
White blood cells are described as the 'soldiers' of the body because it destroys the harmful microorganisms and foreign particles and prevents infection from spreading in the body.
The diagram illustrates the structure of a flower. Label the parts a to e.
The parts labelled a to e are:
a → Petal (corolla)
b → Stigma
c → Anther
d → Ovules
e → Thalamus
Xylem is the food-conducting tissue in plants.
False
Correct statement — Phloem is the food conducting tissue in plants.
Blood group O is a universal donor while AB is a universal recipient.
True
Lymph nodes produce erythrocytes.
False
Correct statement — Lymph nodes produce Lymphocytes.
Ovulation generally occurs on the 14th day of the menstrual cycle.
True
Non-living things in the environment are called its biotic components.
False
Correct statement — Non-living things in the environment are called its abiotic components.
Animals that eat other living animals are called carnivores or secondary consumers.
True
Green plants that fix the solar energy constitute second trophic level.
False
Correct statement — Green plants that fix the solar energy constitute first trophic level.