Science Matters class 7
Q: What is the act of voluntarily giving blood called?
A: Blood donation.
Q: Amoeba do not have well-defined excretory systems. By which process do they get rid of body wastes?
A: Unicellular organisms such as amoeba, paramecium, hydra etc. do not have a well-developed excretory system. They get rid of body waste by simple diffusion. That is the waste products are passed through the cell membrane into the surrounding.
Q: What is the phase of relaxation of heart muscles during a heartbeat called?
A: Diastole.
Q: Name a crystalline waste product in the leaves and stems of plants such as spinach, rhubarb and water hyacinth.
A: Calcium oxalate and calcium carbonate crystals are formed in some plants as waste products. These crystals are found in the leaves and stems of many plants such as spinach, rhubarb and water hyacinth. When the plant gets rid of the waste product, then the leaves fall off.
Q: Differentiate between hematuria and dysuria.
A: Presence of blood in the urine called hematuria. Burning sensation and pain during urination called dysuria.
Q: What is the function of the urethra in the human body?
A: Urethra is the passage between the urinary bladder and the exterior of the body through which urine expelled. Two rings of muscles called sphincters were present at the internal (upper end) as well as the external (lower end) of the urethra which control the passage of urine through the urethra.
Q: State any three situations that require a blood transfusion.
A: Sometimes it becomes necessary to infuse blood into the body of a patient undergoing 1) surgeries 2) childbirth 3) anaemia, undernourished children or treatment for cancer.
Q: What happens to the rate of transpiration if:
i) temperature of a place increases?
A: Rate of transpiration also increase.
ii) humidity of a place increases?
A: Rate of transpiration also decrease.
iii) wind speed of a place decreases?
A: Decreases.
1) How many chambers do you see?
A: Four.
2) How many chambers on the top? What are they commonly called?
A: Two. Right atrium, Left atrium.
3) How many chambers at the bottom? What are they commonly called?
A: Two. Right ventricle, Left ventricle.
4) How many chambers are there on the right? Name them.
A: 2. Right atrium and Right ventricle.
5) How many chambers are there on the left? Name them.
A: Two. Left atrium and Left ventricle.
6) What type of blood reaches the heart – Oxygenated or deoxygenated?
A: Both.
7) Where does deoxygenated blood come from?
A: Various organ and tissue. Vena cava.
8) Which chamber does it enter into?
A: Right atrium.
9) Complete the statement: Right atrium receives deoxygenated blood from the __.
A: body.
10) Name the type of blood vessels that carry deoxygenated blood to the heart.
A: veins / capillaries.
11) Name the special blood vessels that carry the deoxygenated blood to the heart.
A: Superior and inferior Vena cava.
12) Is there any valve present between the right atrium and right ventricle?
A: Yes.
13) Can you name this valve?
A: Tricuspid valve.
14) What is the role of this valve?
A: Unidirectional blood / prevent backflow.
15) What type of blood reaches the right ventricle – oxygenated or deoxygenated?
A: deoxygenated.
16) What happens when the right ventricle pumps the blood?
A: deoxygenated blood is sent to lungs.
17) Name the type of blood vessels that carries blood from the heart to the other part of the body.
A: artery.
18) What is the special name given to the artery that carries deoxygenated blood from the heart to the lungs?
A: pulmonary artery.
19) Complete Statement: __ carries deoxygenated blood from the right ventricle of the heart to the lungs.
A: pulmonary artery.
20) What happens to the blood within the lungs?
A: Carbon dioxide is removed and oxygen is added.
21) What type of blood is transported from the lungs to the heart – oxygenated or deoxygenated?
A: Oxygenated.
22) Name the type of blood vessels that carry blood from the body to the heart.
A: Veins.
23) Name the special blood vessel that carries blood from the lungs to the heart.
A: Pulmonary veins.