How is oxygen and carbon dioxide transported in human beings?

Name the components of xylem and phloem.

Why are the walls of ventricles thicker and more muscular than the walls of atria?

Write two important functions of transpiration in plants .

How do leaves of plants help in excretion?

Why is transpiration important for plants?

Why and how does water enter continuous into the root xylem?

What will happen if platelets were absent in the blood?

Why do veins have thin walls as compared to arteries?

Why is blood circulation in human heart called double circulation?

Differentiate between an artery and vein.

What do the following transport?
(a)Xylem
(b)Phloem
(c)Pulmonary vein
(d)Pulmonary artery

Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?

Name the constituents of blood.Why white blood corpuscles are called 'soldiers of the body'?

The human heart is a muscular organ made up of cardiac muscles. It is a four- chambered organ to prevent intermixing of oxygenated and de-oxygenated blood. A thick wall muscle called septum that separates the two sides left and right of the heart. Look at the picture.

(i) The upper two chambers and lower two chambers are called :

(ii) The artery which carries de-oxygenated blood from the heart into lungs is called :

(iii) Pulmonary vein brings :
(a) oxygenated blood from the lungs to the heart
(b) de-oxygenated blood from the heart to the lungs
(c) oxygenated blood from the heart to the lungs
(d) de-oxygenated blood from the lungs to the heart
(iv) Tricuspid valve is found between :

(v) The de-oxygenated blood from the body organs first enters :
(a) into right atrium of the heart through vena cava.
(b) into left atrium of the heart through vena cava.
(c) into right ventricle of the heart through vena cava.
(d) into right atrium of the heart through aorta.

The tubes – blood vessels - Arteries are the vessels which carry blood away from the heart to various organs of the body. Since the blood emerges from the heart under high pressure, the arteries have thick, elastic walls. Veins collect the blood from different organs and bring it back to the heart. They do not need thick walls because the blood is no longer under pressure, instead they have valves that ensure that the blood flows only in one direction. On reaching an organ or tissue, the artery divides into smaller and smaller vessels to bring the blood in contact with all the individual cells. The smallest vessels have walls which are one-cell thick and are called capillaries. Exchange of material between the blood and surrounding cells takes place across this thin wall. The capillaries then join together to form veins that convey the blood away from the organ or tissue.

(i) A blood vessel which carries blood back to the heart is :

(ii) The blood vessel which carries oxygenated blood from the lungs to the heart is :

(iii) The smaller vessels in which arteries are divided after entering the body organs are called

(iv) After entering into the tissues, the arteries are divided into

(v) The blood vessels in which there are no valves includes

Each capillary cluster in the kidney is associated with the cup- shaped end of a tube that collects the filtered urine (see adjoining figure). Each kidney has large numbers of these filtration units called nephrons packed close together. Some substances in the initial filtrate, such as glucose, amino acids, salts and a major amount of water, are selectively re-absorbed as the urine flows along the tube. The amount of water reabsorbed depends on how much excess water there is in the body, and on how much of dissolved waste there is to be excreted. The urine forming in each kidney eventually enters a long tube, the ureter, which connects the kidneys with the urinary bladder. Urine is stored in the urinary bladder until the pressure of the expanded bladder leads to the urge to pass it out through the urethra. The bladder is muscular, so it is under nervous control, as we have discussed elsewhere. As a result, we can usually control the urge to urinate.

(i) Which of the following is the correct path taken by urine in our body ?
(a) kidney → ureter → urethra → bladder
(b) kidney → bladder → urethra → ureter
(c) kidney → ureter → bladder → urethra
(d) bladder → kidney → ureter → urethra
(ii) The excretory unit in the human excretory system is called :

(iii) The substance which is not reabsorbed into the blood capillaries surrounding the tubule of a nephron is mainly 

(iv) The procedure of cleaning the blood of a person by using a kidney machine is known as :

(v) The kidneys in human beings are a part of the system for

Transpiration is the evaporative loss of water by plants. It occurs mainly through the stoma in the leaves. Besides the loss of water vapour in transpiration, exchange of oxygen and carbon dioxide in the leaf also occurs through pores called stomata. Normally stomata remain open in the day time and close during the night
(i) Which of the following will not directly affect transpiration?

(ii) Water vapour comes out from the plant leaf through the stomatal opening. Through the same stomatal opening, carbon dioxide diffuses into the plant during photosynthesis. Reason out the above statements . using one of following options.
(a) The above processes happen only during night time.
(b) One process occurs during day time and the other at night.
(c) Both processes cannot happen Simultaneously.
(d) Both processes can happen together at day time.
(iii) Which of the following statements is not true for stomatal apparatus?
(a) Guard cells invariably possess chloroplasts and mitochondria.
(b) Guard cells are always surrounded by subsidiary cells.
(c) Stomata are involved in gaseous exchange.
(d) Inner wall of guard cells are thick.
(iv) Which of the following is not a purpose of transpiration?
(a) Helps in absorption and transport in plants
(b) Prevents loss of water
(c) Maintains shape and structure of plants by keeping the cells turgid
(d) Supplies water for photosynthesis
(v) Refer to the given graphs regarding factors affecting transpiration rate and select the correct option.

(a) P-Atmospheric temperature; Q-Atmospheric pressure
(b) P-Relative humidity; Q-Atmospheric temperature
(c) P-Air movement; Q-Light
(d) P-Atmospheric pressure; Q-Relative humidity

Double circulation is a type of circulating system in which the blood passes through the heart twice before completing a full circuit of the body. Blood is pumped from the heart to the lungs and returns to the heart before being distributed to other organs and tissues of the body.
(i) The figure shows blood circulation in humans with labels A to D. Select the option which gives correct identification of label and functions of the part.

(a) B - Capillary- Thin without muscle layer and wall two cell layers thick
(b) C - Vein-Thin walled and blood flows in jerks/spurts
(c) D - Pulmonary vein-Takes oxygenated blood to heart, PO₂ = 95 mm Hg
(d) A - Artery-Thick walled and blood flows evenly
(ii) Incomplete double circulation is seen in

(iii) Which of the following animals shows double circulatory pathway?

(iv) The given figure is of circulatory system. Identify the labelled parts (A-D) from the list (I-VII).

(I) Pulmonary circulation  (II) Systemic circulation  (III) Superior vena cava  (IV) Inferior vena cava
(V) Aorta                           (VI) Veins and venules                  (VII)Arterioles and capillaries

(v) Select the option which properly represents pulmonary circulation in humans.
\(\text { (a) Left auricle } \frac{\text { Deoxygenated }}{\text { blood }}{\longrightarrow} \text { Lungs } \frac{\text { Oxygenated }}{\text { blood }} \text { Right ventricle }\)
\(\text { (b) Left auricle } \frac{\text { Oxygenated }}{\text { blood }}{\longrightarrow} \text { Lungs } \frac{\text { Deoxygenated }}{\text { blood }}{\longrightarrow} \text { Right ventricle }\)
\(\text { (c) Right ventricle } \frac{\text { Deoxygenated }}{\text { blood }}{\longrightarrow} \text { Lungs } \frac{\text { Oxygenated }}{\text { blood }} \rightarrow \text { Left auricle }\)
\(\text { (d) Right ventricle } \frac{\text { Oxygenated }}{\text { blood }}>\text { Lungs } \frac{\text { Deoxygenated }}{\text { blood }} \gg \text { Left auricle }\)