Question 1

Enzymes are proteins. State the chemical elements that enzymes are made from. .............................................................................................................................................

Accepted Answer

All known enzymes are proteins. They are high molecular weight compounds made up principally of chains of amino acids linked together by peptide bonds. Amino acids are small organic molecules that consist of an alpha (central) carbon atom linked to an amino group, a carboxyl group, a hydrogen atom, and a variable component called a side chain.  Therefore the chemical elements that enzymes are made from are- Carbon (C), hydrogen (H), oxygen (O) and nitrogen (N).

Question 2

Xylem is an example of a plant tissue.This list shows examples of tissues, organs and organ systems in humans.Complete the given table using the examples from the list. One has been done for you.

Accepted Answer

The given table can be filled in the following manner-

Question 3

Reproduction is a characteristic of all living organisms.State two other characteristics of all living organisms.1 ................................................................................................................................................ 2 ................................................................................................................................................

Accepted Answer

1. Growth: Increase in mass and number is the characteristic of growth. Multicellular organisms grow by cell division. Plants grow by cell division throughout their life. Animals grow only up to a certain age. Unicellular organisms also grow by cell division.2. Excretion: Have the ability to get rid of waste products.

Question 4

A specialised cell performs a particular function.Sperm and egg cells are two types of specialised cell that are involved in reproduction in humans.State the names of two other specialised cells.1 ................................................................................................................................................ 2 ..............................................................................................................................................

Accepted Answer

A specialised cell performs a particular function.Sperm and egg cells are two types of specialised cell that are involved in reproduction in humans.The other two specialised cells can be:1. Red blood cells: Red blood cells carry oxygen from our lungs to the rest of our bodies. Then they make the return trip, taking carbon dioxide back to our lungs to be exhaled.2. White blood cells: They help the body fight infection and other diseases.

Question 5

State three structures present in both animal and plant cells. 1 ................................................................................................................................................ 2 ................................................................................................................................................ 3 ................................................................................................................................................

Accepted Answer

Three structures present in both animal and plant cells are: 1. Cell membrane 2. Cytoplasm3. Nucleus

Question 6

Three identical potato cylinders were used to investigate water movement in plant cells.Cranberry juice is a red fruit juice that contains natural sugars.Three test-tubes were set up as shown in figure and left for one hour.After one hour the potato cylinders were removed from test-tubes 1 to 3. The mass of each potato cylinder is recorded in the table.(i) Describe the results for test-tubes 1 and 2. test-tube 1 ......................................................................................................................... ........................................................................................................................................... test-tube 2 ......................................................................................................................... ........................................................................................................................................... (ii) Calculate the decrease in the mass of the potato cylinder in test-tube 3. ........................................................g  (iii) Explain why the potato cylinder lost mass in test-tube 3. ......................................................................................................................................  .....................................................................................................................................

Accepted Answer

(i) test-tube 1: Potato cylinder in test-tube 1 is increased in mass by 5g.    test-tube 2: Potato cylinder in test-tube 2 stayed the same.(ii) mass of the potato cylinder at the start/g in test-tube 3 = 25     mass of the potato cylinder after one hour/g in test-tube 3 = 19     The decrease in the mass of the potato cylinder in test-tube 3 = 25-19 = 6g(iii) The potato cylinder lost mass in test-tube 3 by the process of osmosis. Water moves out of the potato cylinder by osmosis because there is more water inside the potato than in the solution.

Question 7

State the name of one mineral ion and give a reason why it is important for plant growth. ion ............................................................................................................................................. reason .......................................................................................................................................

Accepted Answer

Magnesium ions are needed by plants. Magnesium is the central core of the chlorophyll molecule in plant tissue. Thus, if Mg is deficient, the shortage of chlorophyll results in poor and stunted plant growth. Magnesium plays an important role in activating enzymes involved in respiration and nucleic acid synthesis. Magnesium is mobile within the plant so deficiency symptoms appear first in older leaves. The symptoms show up as yellow leaves with green veins (i.e. interveinal chlorosis).

Question 8

Several processes occur in the alimentary canal.(i) The boxes on the left show the names of processes that occur in the alimentary canal. The boxes on the right show descriptions of processes that occur in the alimentary canal. Draw five straight lines to link each process with its description. (ii) State the name of one type of digested food molecule that is absorbed. .....................................................................................................................................

Accepted Answer

(i)(ii) Proteins undergo hydrolysis, which converts them into amino acids, during digestion. The amino acids are dissolved in our blood and transported to organs and tissues. The amino acids are either converted into energy or put together into proteins using condensation polymerization.

Question 9

Transpiration is the loss of water from plant leaves.Complete the sentences using the words and phrases from the list.Each word or phrase may be used once, more than once or not at all.Water on the surface of ........................................................ cells ........................................................ . The water vapour moves out of the leaf by ........................................................ into the atmosphere through openings in the leaf called ........................................................ .

Accepted Answer

Water on the surface of spongy mesophyll cells evaporates. The water vapour moves out of the leaf by diffusion into the atmosphere through openings in the leaf called stomata.

Question 10

A student compared the mass of water lost from four leaves.Four similarly-sized leaves were collected from the same plant.Some of the surfaces of the leaves were covered with a waterproof substance. The mass of each leaf was measured.The leaves were hung on a piece of string, as shown in figure below. The leaves were left for several hours and the mass of each leaf was measured again. The results from the experiment are shown in given table .(i) Calculate the difference in mass for leaf F and write your answer in the table.  (ii) Describe how the different treatments of the leaves affected their loss of mass.         Use the information in figure and table to support your answer.      .....................................................................................................................................  (iii) Suggest a reason for the difference in mass lost between leaves G and H.       .....................................................................................................................................

Accepted Answer

(i)(ii) F- In this case the leaf was not covered with any any waterproof substance. Hence, there is loss of water from the surface of leaf via process of transpiration through stomata and the mass of leaf reduced from 0.67g to 0.40g after several hours.G-  In this case the lower surface of leaf was covered with waterproof substance. In a dorsiventral leaf more stomata are present on lower surface as compared to upper surface. As the lower surface was covered, hence water was lost from the upper surface of leaf only. Therefore, there was a very slight difference in mass of leaf (0.03g).H-  In this case the upper surface of leaf was covered with waterproof substance. Here, the lower surface having more stomata is left exposed and more water is lost via transpiration. That is why the mass of leaf decreased significantly (0.25g) after several hours of treatment.J- In this case both the surface (i.e., upper and lower) are covered with waterproof substance. There is no loss of water as the stomata are not exposed. Hence, there was no change in mass of leaf even after several hours.(iii) As in a dorsiventral leaf more stomata are present on lower surface as compared to upper surface. Therefore, water loss was more in case of H as compared to G. That is why the loss of mass after several hours is more in leaf H (0.25g) and less in leaf G (0.03g).

Question 11

Figure below is a photomicrograph of a cross-section of part of a leaf.(i) State the letter on the figure which identifies a cell where photosynthesis occurs. ...............  (ii) State the letter on the figure that identifies the part of the plant that transports water from the roots to the leaves and state its name. ............... name .................................................................................................................................

Accepted Answer

(i) The letter K identifies the mesophyll cell where photosynthesis occurs.
(ii) The letter L identifies the part of the plant that transports water from the roots to the leaves. Its name is Xylem tissue.

Question 12

Figure below is a drawing of a bacterial cell.State three ways in which a plant cell is similar to the bacterial cell shown in figure. 1 ................................................................................................................................................ 2 ................................................................................................................................................ 3 ................................................................................................................................................

Accepted Answer

Similarities between plant cell and bacterial cell are:
1. Presence of cell wall in both the cells.
2, Presence of genetic material (DNA) in both plant and bacterial cell.
3. Presence of cytoplasm in both the type of cells.

Question 13

Pathogens for transmissible diseases can be transmitted either through direct contact or indirect contact.Table given below gives examples of ways in which pathogens can be transmitted.Identify the examples of direct contact by placing a tick (✓) in the correct boxes in table.

Accepted Answer

Direct contact for transmissible diseases includes touching, kissing, sexual contact, contact with oral secretions, or contact with body lesions. Indirect contact infections spread when an infected person sneezes or coughs, sending infectious droplets into the air.

Question 14

List two features of human gas exchange surfaces. 1 ................................................................................................................................................ 2 ................................................................................................................................................

Accepted Answer

Two features of human gas exchange surfaces are:
1. Large surface area to allow faster diffusion of gases across the surface.
2. A good blood supply network.

Question 15

Carbon dioxide is excreted through the lungs. (i) Describe a chemical test that would identify that the gas excreted through the lungs is carbon dioxide. chemical test ..................................................................................................................... ........................................................................................................................................... positive test result ............................................................................................................. ........................................................................................................................................... (ii) There are differences between the composition of inspired and expired air. Table given below shows four of the gases that make up air and the percentage of each gas that is in inspired and expired air. Use numbers from the list to complete the table. Each number can be used once, more than once or not at all.(iii) State the name of gas Z shown in above table. .....................................................................................................................................

Accepted Answer

(i) Chemical test : Limewater can be used to detect carbon dioxide. Positive result: If carbon dioxide is bubbled through limewater then it turns from clear to cloudy/milky in colour. (ii) In expired air the percentage of carbon dioxide is 4%.In inspired air the percentage of oxygen is 21%.So the table can be completed by: (iii) The gas Z shown in the table could be water vapour as the the percentage of water vapour in inspired air varies and the percentage increases when expired.

Question 16

An athlete measured his breathing rate during 12 minutes of exercise.The results are shown in given figure(i) Describe the changes in the breathing rate, while the athlete was exercising, shown in the figure. ..................................................................................................................................... (ii) Calculate the percentage change in the breathing rate between 0 and 10 minutes. Give your answer to the nearest whole number. Show your working. ............................................................ % (iii) The activity of the heart can also be used to monitor the effects of physical activity. State two methods that can be used to monitor the activity of the heart. 1 ........................................................................................................................................ 2 ........................................................................................................................................

Accepted Answer

(i) The body demands more amount of O2​ while exercising hence it increases the breathing rate. When the breathing rate increases, the duration of single inhalation becomes shorter while the number of inhalation increases. In the given figure, while exercising the athlete experiences an increase in it's breathing rate or the number of breaths per minute. In the initial minutes (up to 5 minutes of exercising) the breathing rate was 10-15 breaths per minute but with continuous exercising for 10 minutes, the breathing rate of the athlete had reached 25 breaths per minute. (ii) Percentage change can be calculated by the formula: ∣V1​∣(V2​−V1​)​×100  where, V1​ is the initial value andV2​ is the changed value.In the given figure the initial value of breathing rate is 10 breaths per minute and after 10 minutes the breathing rate changes to 25 breaths per minute.So, by taking the value of V1​= 10 and V2​= 25, we get=∣10∣(25−10)​×100 =1015​×100 =1.5×100 =150% change . So we can conclude that there is an 150% increase or change in the breathing rate between 0 to 10 minutes of exercising.(iii) The activity of the heart can also be used to monitor the effects of physical activity. Two methods that can be used to monitor the activity of the heart can be:1. Checking the pulse with a stethoscope.2. Monitoring the heart rate with a chest strap or fitness tracker.

Question 17

The diet of a woman is very important during pregnancy. (i) State the name of one component of a pregnant woman’s diet that is needed for the formation of bones in the fetus. .....................................................................................................................................  (ii) State the importance of iron in a pregnant woman’s diet. .....................................................................................................................................  (iii) State one source of iron in the diet. .....................................................................................................................................  (iv) State why women are often advised to avoid alcohol consumption during pregnancy.  .....................................................................................................................................

Accepted Answer

(i) Calcium(ii) During pregnancy, iron is needed primarily to supply the growing fetus and placenta and to increase the maternal red cell mass/ haemoglobin .(iii) Green vegetables(iv) Women are  strongly advised to not drink alcohol during pregnancy because there may be an increased risk of miscarriage. It might crosses the placenta and may cause harm to the fetus.

Filters

Filters

class

Class 11

Class 12

Middle School

Grade 12

Class 10

Class 9

Grade 11

IBDP

Class 6

Grade 10

Grade 9

Class 8

Class 7

High School

subject

Chemistry

Physics

Biology

Mathematics

difficulty

easy

medium

hard

Solutions for Grade 9 Important Questions

Found the solution, but did not understand the concept?

Ask my first question