Biology Past Papers (Grade 6) - PDF

 Chapter Question 5 5 1 (2/2013) (3/2020) What is the chemical structure of the prokaryotic cell wall? Answer protein, lipids and polysaccharides....

 Chapter Question 5 5 1 (2/2013) (3/2020) What is the chemical structure of the prokaryotic cell wall? Answer protein, lipids and polysaccharides. (2022.1, 2023. 1) Question 6 6 What are the characteristics of the Prokaryotic cell ? Answer 1 Prokaryotic cell has genetic material without a membrane and it is called as nucleus zone or Nucleoid. 2 Prokaryotic cell cytoplasm has no membranous organelles like Golgi bodies and mitochondria, yet. It has ribosome in the form of numerous small grains, which build proteins. 3 Prokaryotic cell is represented by blue green algae, bacteria and Mycoplasma which all belong to Monera. (2013/ 2) (2015/1 (2015) 2O) (2016.1) (2017. 2 Mosul) (2019.2) (2021)p , 2021.2 Supplementary) 2024 P Question 7 7 Draw a prokaryotic cell (bacteria) and label the parts. Answer 2 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter Question 12 12 1 (1/1987) (2/1988) (1/2000) What is the location and importance (function) of the plasma membrane? Answer location: It Is surrounding the cytoplasm in all cells. The function: allows the exchange and movement of some molecules (water and dissolved materials) between the cell and the external environment. (1/2009) (2017/3 Questions of Mosul) (3/2019) Question 13 13 Defined the plasma membrane? Answer It is a cellular membrane surrounding the cytoplasm in prokaryotic and eukaryotic cells it is a flexible, thin and fluid membrane (semi-permeable) unseen by light microscope; it can be seen by electron microscope. the plasma membrane consists of two thin layers of phospholipids with hydrophilic end and hydrophobic end. The two layers are separated by protein particle that allows and controls passage of materials. (1/1991) (1/1/2003 Question 14 14 Compare between the plasma membrane and the cell wall? Answer Plasma Membrane Cell Wall Surrounding the cytoplasm in Cell wall exists only on plant cells prokaryotic and eukaryotic cells. It is a flexible, thin Thick wall Fluid membrane(selectively Full permeability membrane) Plasma membrane consists of two Has three layers: Middle Lamella , thin layers of phospholipids with Secondary Wall ,Primary Wall hydrophilic end and a hydrophobic end. The two layers are separated by protein particle that allows and controls passage of materials. Its function is to regulate the Cell wall provides protection and exchange of materials between the support to plasma membrane and cell and the external environment cytoplasm 4 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter 1 Endoplasmic reticulum Question 18 Define : 1 Endoplasmic reticulum?  (2/1992) (2/2010 Special) 2 Ribosomes? 2015/1 (O.C) Answer 1 E  ndoplasmic reticulum: has reticulate interconnected system of tubules and vesicles, attached to plasma membrane at certain places and attached to nuclear membrane at other places. Endoplasmic reticulum is the place where lipids, carbohydrates and proteins are made. It is called Endoplasmic reticulum because of Branches and interlocks with each other. Endoplasmic Reticulum is divided into two types rough and smooth Endoplasmic Reticulum 2 Ribosomes: Are small particles found on the surfaces of RER tubules and they also found freely in the cytoplasm of the cells (also found in the cytoplasm of prokaryotic cells) ribosomes derived from nucleolus they composed of ribosomal RNA (rRNA) and protein,its function is protein synthesis Question 19 Fill in the following blanks:- 1 The endoplasmic reticulum is divided into two types? 2017/1, 2020/1 , ? 2024/p 2 The rough endoplasmic reticulum is characterized by Answer 1 the rough and the Smooth endoplasmic reticulum 2 its surfaces contain ribosomes that represent sites of building proteins. (1/1989) (2/1991) (1/1992) (2/2005) (1/2007) (2/2015) (1/2005) Question 20 20 What is the location of the ribosomes? Answer found on the surfaces of RER tubules and they also found freely in the cytoplasm of the cells (also found in the cytoplasm of prokaryotic cells) Question 21 What is the function of the smooth endoplasmic reticulum?  (1/1995) (2014/Introductory questions) Where is the smooth endoplasmic reticulum abundant? And what is its importance?  (2/2014) Answer S.E.R appears in cells of ovary, testicles and two adrenal glands. Their importance; 1 transfers materials inside the cell. 6 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter Question 26 26 1 (1/1992) What are the functions of the Golgi apparatus in animal cells? Answer 1 Build and secrete complex sugars 2 Secrete protein, which is obtained from endoplasmic reticulum but it does not produce protein. 3 Secrete many materials like hormones and enzymes Question 27 What is the location of 1 Cisternae? (1/2012) 2 Golgi apparatus? (2014/Introductory questions) Answer 1 in the Golgi apparatus. 2 Golgi apparatus has special location in the cytoplasm between the nucleus and plasma membrane. Question 28 What is the location of the Dictyosome?  (2/1988) What is the function of the Dictyosome?  (1989/2) (1/1992) (2/1992) (1/2003) (2007/1) ( 2/2013) (1/2017 Mosul questions (( 2/2018)) (1/2019) O.C (3/2020) Answer Location: The Dictyosome found in the cytoplasm of the plant cells. Function: responsible for building cellulose and some components of cell wall. Question 29 What does the Golgi apparatus consist of? Or Explain the components of the Golgi apparatus.  (2022. 2 Distinguished) Answer Golgi apparatus consists of three chambers marked by smooth membranes, the first is (3 to 10) flat saccules called cisternae, the second is vesicles and the third is large vacuoles. Question 30 What are the components of the Golgi apparatus? What are its functions in animal cells?  (2018/O.C.C) 2022.1 Answer Golgi apparatus consists of three chambers marked by smooth membranes 1 the first is (3 to 10) flat saccules called cisternae, 2 vesicles. 3 large vacuoles, 8 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter Question 34 1 What is the location and function (importance) of 1 Mitochondria? 2013.p, 2014.3 (2016/p 2 Cristae?  (1/2003) (3/2014) (1/2016) (1/2017 Mosul (2/2020 supplementary) Answer 1 Location: Mitochondria are found in eukaryotic cell. Function: Cellular respiration and involved in producing high-energy Adenosine tri-phosphate (ATP). 2 Location: T  hey are curves and bends of the inner membrane of the mitochondria, topes of these curves and bends are towards the mitochondria cavity Function: they increase the surface area of the inner layer of Mitochondria. 2019/ Introductory questions Question 35 35 What is the origin of cristae? Answer Origin: the inner membrane of mitochondria. (2015. 2.O ) Question 36 36 Who is responsible for increasing the surface area of the inner layer of the mitochondrial membrane? Answer Cristae Question 37 Give the reasons for each of the following? 1 the presence of cristae in mitochondria? (2014. 2) (2017. 2) (2018.2) (2024 2 Mitochondria are known as the energy houses in the cell? (1/2017) O.C) 3 The base function of mitochondria is cellular respiration.  (1.2014) (3.2015) (2016.1) (2024)(1.2023) (2.2020) (3-2018) 4 There are a large number of mitochondria in in muscle. (Book questions) Answer 1 to increase the surface area of the inner layer of the mitochondrial membrane. 2 because they are involved in producing high-energy Adenosine tri-phosphate ATP 3 because it produces respiratory enzymes 4 Because the muscle needs energy during work and the mitochondria are involved in producing high-energy Adenosine triphosphate (ATP). Thus, the basic function of mitochondria is cellular respiration, because they have respiratory enzymes. 10 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter 1 3 T hylakoid Membrane: A capsule structure formed by the inner membrane of the chloroplasts. It contains chlorophyll and enzymes, which help in photosynthesis. Question 41 who is responsible for each of the ? 1 The white color of the potato 1/2010. 1/2014. 3/2016 2 The colors of flowers and fruits. (2/2017 O.C). Answer 1 It contains a large number of leucoplasts and full of starch. 2 Chromoplasts. Question 42 What is the location of: 1 Thylakoid (1.o/2017) 2 Vegetative Fat  (1.D/2023) Answer 1 inner membrane of the chloroplasts 2 Leucoplast Question 43 What is the location and importance (function) 1 leucoplast. (2015/p) (2017/1 Questions of Mosul) (2019/p) (2020/p) (3/2015) 2 chloroplast (3/2017) 3 Grana (1/1988) 4 Chlorophyll (1.M/2023) Answer 1 There are in the cytoplasm of plant cells such as potato They are centers for converting glucose sugar into polysaccharide like starch or into fats or proteins. 2 in cytoplasm of plant cells, they Contribute to the process of photosynthesis. 3 inside duel layer membrane of chloroplast. They contain chlorophyll and enzymes that contribute to the photosynthesis process. 4 In Grana, Absorb solar energy 12 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter 1 surrounded dual layer membrane. Inside the membrane, there are two structures: the Granum (pl. Grana) and Surrounded by a double layer the stroma. membrane The inner membrane contain : A The inner membrane has crests that capsule structure called Thylakoid increase the surface area of the inner Membrane layer Contain Chlorophyll Does not contain chlorophyll Perform the function of cellular Perform photosynthesis respiration (2016 p , 2017.2, 2020.2, 2023p) Question 48 48 Draw a diagram showing the structure of the chloroplast. Answer Lysosomes Question 49 Define 1 lysosomes? (1/2001) (2/2016) (2/2017) 2 Autolysis? (1/1988) (2/1992) (1/1998) (1/2008) 1/2023 Answer 1 They are vesicles surrounded by mono-layer membrane. It contains many lysis enzymes (over 40 enzymes),these enzymes are responsible for digestion in the cell. Lysosomes are found in almost all cells, especially those that have the ability for phagocytosis like neutrophils. 14 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter 1 2 because It cleans cell cytoplasm from food particles, mitochondria pieces, microorganisms and other. 3 Because the lysosomes in the tail cells destroy these cells by releasing enzymes from the lysosomes to the cytoplasm of the cell, and this results in the digestion of the cytoplasm. contents of large molecules and thus the death of the cell and disappearance of the tail (3/2017)(2/2020 «O.3/2019, 2/2016 Question 53 53 Who is responsible for the Metamorphosis. Answer lysosomes. Question 54 Give example for each of the following: Metamorphosis Answer The disappearance of the frog larvae tail disappear when becoming adult frogs. 1/2019 Question 55 55 Fill in the following blanks: Lysosomes are found in ? Answer They are found in cells that have ability for phagocytosis like Neutrophils 2015.1.O Question 56 56 compare Between Lysosomes and Golgi apparatus Answer lysosomes Golgi apparatus They are vesicles surrounded by mono-layer Golgi apparatus consists of three membrane. chambers marked by smooth membranes, the first is called cisternae, the second is vesicles and the third is large vacuoles. Lysosomes are found in almost all cells, It has a special location in the especially those that have the ability for cytoplasm between the nucleus phagocytosis, like neutrophils. and plasma membrane. It has the ability for phagocytosis It is a secretary apparatus 16 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter 1 Cytoskeleton Question 58 Define Each of the following: 1 Microfilament? (3/2014) (1/2019) O.C (2/2020) 2 Centrosome? (1/1987) (1997/2) (1/2012) (3/2014) 3 Kinetosome (basal body)?  Introductory questions) (1/2014 questions of the displaced)) (2/2020 «Supplementary») 2006, (2/2002, 2/1997) Answer 1 They are thin and straight structures that were first observed in muscle cells, and they are represented by actin filaments consisting of actin protein and myosin filaments, which contain the myosin protein both are responsible for expansion and contraction of cell. 2 It is a living organelle in the cell, it has a pair of centrioles, each of which is a cylinder consisting of nine triple- groups of microtubules. The centrosome doubles during cell division; the two centrosomes move a part to the opposite sides the cell and connect together through spindles fibers. 3 It looks like centriole in structure. It is located at the base of the cilium in cells, which contain cilium, or flagella, The kinetosome has a vital role in movement of cilium and flagella. Question 59 What is the location and importance (function) of: 1 Microfilamentts?  (Questions of the Displaced) (3/2017 Questions of Mosul) 1/2015,3/2013, (2018/ Introductory questions) (3/2020 2 micro-tubules? 2016/ Introductory questions 2024.1 3 kinetosome (basal body)? (2018/3) ((3/2019)) 4 centrosome? What is its origin? (2006.2) Answer 1 location: It was first clearly observed in muscle cells function: responsible for the cell›s ability to contraction and expansion 2 1 chromosome movement during cell division. 2 they are important for cytoskeleton. 3 organization and transfer of materials. 4 They are major elements in formation of cilium and flagella. 5// form the centrosomes 3 It is located at the base of the cilia or flagella in cells that contain cilia or flagella. function// plays an important role in the movement of cilia and flagella. 4 Exist in animal, cell cytoplasm and other primitive organisms like algae and fungi, are situated near the nucleus. 18 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter 1 Exist in animal, cell cytoplasm and other first observed in Location primitive organisms like algae and fungi, muscular cells are situated near the nucleus They are actin filaments, which contain actin chemical protein, and Protein called tubulin. composition myosin, which contains myosin protein. 1  lay vital role in chromosome p movement during cell division It is responsible 2 They are important for cytoskeleton for expansion Function 3 Organization and transfer of materials and contraction 4  hey are major elements in formation T of cell. of cilium and flagella. 5 Which and form the “centrosomes Vacuoles (2/1991 ) (2022/p) (2024/p) Question 65 65 What is the location and importance of contracting vacuoles? Answer drain the cell from surplus water in protista In amoeba and paramecium. (1/1989) (1/1991) ( 1/2020) Question 66 66 who is responsible for: 1 drain the cell from surplus water in protista? 2 maintaining the water balance in paramecium? Answer contractile vacuoles. 20 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter 1 Nucleus Question 71 Give an Example for each of the following: 1 An animal cell without a nucleus.  (1/2008) (2/2010) (1/2014 )2008.1 , 2010.2, 2014.1 2023.1 2 Cell with di-nuclear  1/2021 3 A nucleus containing four nuclei. (1/1990) (2/1994) (2/2014) (1/2018) 4 somatic cell contains 26 chromosomes (2/2014) 5 somatic cell contains 46 chromosomes (2/2020) Answer 1 Mature red blood cells 2 cartilage cells, liver cells and muscle cells. 3 the nucleus of the onion cell. 4 Somatic cells in a frog. 5 somatic cells in a human. (1/2016) Question 72 72 What is the characteristic of the fatty cell nucleus? Answer flattened and located on the cell periphery. Question 73 Give reasons for each of the following 1 The most important component of a living cell is the nucleus? (2016/3 O.C) 2 Cell nuclei show a variation in their shapes. (Chapter questions) (2/2017 O.C) 3 The nucleolus is the center of the formation of ribosomes. (2/2004) 4 Chromosomes are very important : 2023.3 / 2021.2 Answer 1 The cell survival depends on exchanges between the nucleus and cytoplasm,and the cell without nucleus lives for a short time then degenerates like adult red blood cells. 2 Because the shapes of cells differ from each other according to the function that they perform, so the shape of the nucleus adapts to the shape of the cell it might be spherical or oval or lobed or irregular like white blood cells 3 This is because it contains protein and RNA, which works on building rRNA and thus forming ribosomes. 4 because of vital role in genetics, reproduction, development and mutation. 22 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter Question 76 76 1 (1/2017, Mosul questions) (2/2019) (2/2020) p/2020) What is the function of the nucleolus? Answer it has an important role in the formation of ribosomes in which protein is formed. Question 77 What is the origin of: 1 Ribosomes? ( 2016/Introductory questions)( 1/2019) (3/2019) 2 Chromosomes? (2015/Introductory questions)(3/2016 Answer 1 the nucleolus 2 chromatin network. (2/2013) (2017/Introductory questions) Question 78 78 What is the chemical structure of the nucleolus? Answer protein and RNA Question 79 Choose the correct answer: 1 T he number of chromosomes in the somatic cells of the home fly is (46,12,80). (1/2018 O.C) 2 The number of chromosomes in the somatic cells of the frog is (64,80,26). (3/2020)) Answer Question 80 Fill in the following blanks :- 1 There are cases in which cells are di-nuclear, as in? 1/2019, 1/2015 2 The nucleus takes a central position, as in (1/2020) 3 Ribosomes and chromosomes arise from ? (2/2015) 4 The lest number of chromosome in living things is (1/2017 O.C 5 The number of chromosomes in human somatic cells (1/2017) 6 The number of chromosomes in protective cells and in somatic cell is? (1/2021 Answer 1 There are cases in which cells are di-nuclear, as in the cells of cartilage, liver and muscle cells. 24 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh Chapter Question 82 82 1 2018.3 / 2020.1 Compare between Ribosomes and Chromosomes. Answer Ribosomes Chromosomes Located in the cytoplasm on the tubules of rough endoplasmic In the nucleus of eukaryotic cells and reticulum in eukaryotic cells. And in nucleoid of prokaryotic cells within distributed in the cytoplasm of chromatin network. prokaryotic cells. They carry genes which transport genetic features from one generation Responsible for protein formation. to another, and play a vital role in genetics, reproduction, development and mutation. Produced by the nucleolus Produced by chromatin network. They are many in number. The number is fixed in each organism. Small granular structures. Rod-like Rod-like structures structures Cell activities Question 83 Define: 1 Diffuseon? (2/2017 O.C) 2 Permeability? (2/2015) 3 Osmosis? (2/1988)(2/2001)(2/2005) (1/2008) (1/2014) (1/2020) 4 Plasmolysis? (1/1/2015 questions of the displaced )) (2/2015) Answer 1 It is the movement of ions and particles in a certain medium, from high concentration regions to low concentration regions. 2 It is the exchange of materials between the cell and its environment by aid of plasma membrane. The cell can absorb food materials in an appropriate food medium. These materials must pass through the plasma membrane and should have certain solubility in water to pass this membrane. 3 It is the movement of water particles through selectively permeable membrane (plasma membrane) according to variance in concentration. Movement of water particles is done according to diffusion law, because osmosis is a case of diffusion. 26 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter Question 86 86 1 (chapter questions) Compare between semi-permeable membranes and selectively Permeable membranes? Answer Semi - permeable membranes: These membranes do not allow equal passage of solutes as level of solvents. Selectively Permeable: (cell membrane) these membrane allow selective passage of materials according to size of their particles. 2/2022 Question 87 87 List only the types of membranes according to their permeability. Answer 1 Permeable membrane: These membranes allow passage of materials regardless of their structure and size. 2 Semi-permeable membranes: These membranes do not allow equal passage of solutes as level of solvents. 3  Selectively permeable membranes: These membranes allow selective passage of materials according to size of their particles. 4 Non-permeable membranes: Like nylon. (1/2022) The cell distention and then rupture if put in hypotonic solution (2/2017 O.C) Question 88 88 What are the types of solutions according to their osmotic concentration, mention the names of two processes that occur in two types of solutions? Answer 1 The isotonic solution , the concentration of water outside the cell is equal to concentration of cell cytoplasm, the cell neither loses nor gains water. 2 Hypotonic Solution: this solution has low concentration of non-permeable solutes compared to solutes in cytoplasm. The cell gains water, this leads to distention of the cell and then rapture.. 3  Hypertonic Solution: this solution has high concentration of solute materials compared to cytoplasm, thus, direction of water is from cytoplasm to be outer solution, this causes shrinkage of the cell (2/2017 O.C ) Question 89 89 Who is responsible for: controlling the process of passes of substances through the plasma membrane Answer permeability 28 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter Question 94 1 Define: 1 Active transport? (1/1988) (2/2002) (2/2003) (1/2005) (2/2016) (2019 / Introductory questions) 2021.1 2 Carriers 2022.2 3 phagocytosis? (Introductory 2013) (2/2014) (2018 /3) (1/2019) 2021.2 4 pinocytosis? 1/2015, 1/2016, 1/2020 Answer 1 It is the phenomenon of the cell absorbing materials from the outside environment, although, the concentration of these materials inside the cells is higher than outside. To perform this process, there must be carriers in cell membrane. These carriers can move inside and outside the cell. The carrier integrates with other material (particle or ion) needed by the cell. This carrier moves to the inner surface of the membrane. The carried material separates inside cytoplasm. This process requires energy, which is supplied by ATP. 2 protein found in the cell membrane can move inside and outside the cell, the carrier integrates with other material (particle or ion) needed by the cell, this carrier moves to the inner surface of the membrane, the carried material separates inside cytoplasm. 3 phagocytosis (cellular eating): it is a common way of eating (nutrition) among protists like amoeba. It is also used by white blood cells in devouring remaining cells and germs in the blood. This process is done when cell membrane is pouch-like that surrounds the solid matter, then this pouch separates from cell surface and moves inside cytoplasm. The contents are digested by the enzymes secreted by lysosomes in the cytoplasm. 4 It is one of the cell activities ,similar to phagocytosis. When a liquid material is taken, there will be a small hole in cell membrane, this hole surrounds the liquid matter, and becomes inside a pinocytic vesicle. This vesicle separates from cell membrane and moves inside the cell. Question 95 Give the reasons for each of the Following: - 1 cells absorb materials from the outside environment, in spite of , the concentration of these materials inside the cells is higher than outside?. (Questions of the Book) (1/1993) 2 T he cells that perform the active transport process have a lot of mitochondria?  (1/1996) (2/1999) (1/2004) (1/2006) Answer 1 Because there are carriers in the cell membrane. These carriers can move inside and outside the cell. The carrier integrates with other material (particle or ion) needed by the cell. This carrier moves to the inner surface of the membrane. The carried material separates inside the cytoplasm. This process requires energy, which is supplied by ATP, this process called active transport. 2 This process requires energy( ATP) , which is supplied by Mitochondria. To perform active transport there must be carriers in the cell membrane and requires energy (ATP).  Blank 2022.1 30 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter Question 99 99 1 (2015/O.C.C) (1/2016 questions outside )the country Compare between phagocytosis and pinocytosis? Answer Phagocytosis Pinocytosis 1 it cellular eating(solid material is 1 liquid material is taking taking) 2 t his process done when a small 2  his process is done when the T hole in the cell membrane, this hole cell membrane is pouch-like that surrounds the liquid matter, and surrounds the solid matter, then becomes inside a pinocytic vesicle. this pouch separates from the This vesicle separates from the cell cell surface and moves inside the membrane and moves inside the cytoplasm. cell. 3  he contents are digested by the T enzymes secreted by lysosomes in 3 not need enzyme. the cytoplasm. 2016.2 Question 100 100 Draw the active transport Answer 32 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh Chapter 1 Cell Metabolism Question 103 Define: 1 Cell Metabolism.  2020.1 / 2021.2 2 glycolysis? (2/1988) (1/1992) 3 anaerobic respiration? (1/1999) 4 alcoholic fermentation (2/2020) 5 the Krebs cycle?  (2/2000) 6 key to the Krebs cycle? (2/2009) Answer 1 C  ell metabolism is represented by all the chemical changes which take place with the help of enzymes. These changes are catabolism which means degradation of materials and anabolism which means building new things. 2 Glycolysis: It is the process of transforming the Glucose that is the primary respiration material; it undergoes a series of reactions to transform into two molecules of Pyruvic. This process is performed in cell cytoplasm because there are enzymes. 3 Anaerobic respiration: Is the process of creating energy without the presence of oxygen. Occurs in the cytoplasm and the organisms that use it: yeast, green plants, some types of bacteria, and examples are: alcoholic fermentation and lactic fermentation. 4 Alcoholic fermentation: It is a type of anaerobic respiration that occurs in yeast and green plants when there is a lack or absence of oxygen, and in some types of bacteria, The pyruvic acid is oxidized by taking of CO2 molecule. then reduced by hydrogen from glycolysis, turning it into ethyl alcohol 5 T he Krebs cycle is an oxidation process in the presence of oxygen that takes place inside the mitochondria with the aid of a group of special enzymes that begin with the acetyl-CoA ,which is considered the key to the Krebs cycle that unite with oxalo acetic acid to form citric acid. As oxidation continues, oxidation is formed. Alfa ketoglutaric acid 6 T he key to the Krebs cycle is a compound of acetyl-Co A resulting from the oxidation of pyruvate inside the mitochondria. This compound enters the Krebs cycle in a series of reactions leading to the release of the energy amounting to 12 ATP in each cycle. 34 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter Question 113 113 1 1/2017 (Ministerial fee (1/1990) (1/1993) (1/1995)(2/1995) (2/2011) (1/2016) O.C Explain in diagram of the Krebs cycle? Answer Question 114 Fill in the following blanks with appropriate ones: 1 Anaerobic respiration is of two types (2019 /p) 2 The amount of energy released from? (2019 p) 2015 p) 3 In aerobic respiration, acetyl-Co- is involved in? (1/1987) 4 The energy resulting from glycolysis and from aerobic respiration equals (11/2016) 5 The energy resulting from alcoholic fermentation and from aerobic respiration equals  (1/2019) outside the diameter) 6 Energy released from alcoholic fermentation and from one Krebs cycle  (3/2019) (2/2020) 7 The final product of the glycolysis process is? Answer 1 alcoholic fermentation and lactic fermentation 2 the Krebs cycle 12 and in glycolysis 2 3 In aerobic respiration, acetyl-Co- is involved in a series of changes within the mitochondria within the Krebs cycle 4 The energy resulting from glycolysis equals 2ATP and from aerobic respiration equals 38 5 The energy resulting from alcoholic fermentation equals 2ATP and from aerobic respiration equals 38 6 Energy released from alcoholic fermentation 2ATP and from one Krebs cycle 12 ATP 7 The final product of the glycolysis process is the formation of two molecules of pyruvic acid and two molecules of ATP. 40 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter Question 118 1 Fill in the following blanks: 1 The process of cell division takes place during (2/2016 O.C) 2 The time for cell division varies according to 2017/3. 2021.1 3 Cytoplasm divides in the telophase in plant cell by 2018/3 Answer 1 The process of cell division takes place during four phases preceded by an interphase 2 The time for cell division varies according to type of cell, tissue and age of the organism. 3 Cytoplasm divides in the telophase in plant cell by formation of cell plate and in animal cell by constriction of cell membrane. (2017/O.C.C) Question 119 119 What are the most important events that occur in the interphase, a Answer The nucleus is relatively large compared to nucleoli in divided cells. In addition, during this phase, 1 the cell creates huge molecules of nuclear acids and proteins as preparation for division. 2 This phase is characterized by doubling DNA. 3 The centrosome also doubles during this phase. Question 120 In which phase or stage does each of the following occur: 1 Building proteins. 2016.1 / 2021.p 2 Doubling DNA. 2015.2 2018.p 3 Doubling the centrosome. 2017.2 2022.1 4 Aster (astral filaments). 2019,1 , 2022.1 5 Spindle filaments. 2015.1 , 2016.2 6 Disappearance of nucleolus. 2015.2 , 2016.1 7 Disappearance of nuclear membrane. 2015.1 8 Formation of nucleus or nuclear membrane. 2016.1 9 Formation of cell plate. 2021.p 2022.1 10 Disappearance of spindle filaments 2013.1 Answer 1 Interphase 2 Interphase 3 Interphase 4 prophase 5 prophase 6 prophase 7 prophase 8 Telophase 9 Telophase 10 Telophase 42 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter Question 124 124 1 2014.3 / 2017,1 Compare between Centrosome and Centromere. Answer Centrosome Centromere in the cytoplasm of animal in chromosome. Location cells. has a role in cell division, the 1  entromere connects the C centrosome duplicate during sister chromatids to each cell division and the two other. Function centrosomes move apart to 2  hromosomes attach to C the opposite sides of the cell spindle filaments by their and connect together through centromere. spindle fibers 2016.1 / 2017.2 Question 125 125 Explain the metaphase of mitosis. Answer Chromosomes shrink and thickened at this phase. They are located at equator line of cell. Chromosome attach to spindle filaments fibers by their centromere. 2020/2, 2022/2) (2022/1) Question 126 126 What are the theories that explain chromosome movement to cell poles? Answer 1 Spindle filaments are thought to shrink when there is ATP, and they pull chromosomes toward the poles. 2 Spindle fibers form a path so that chromosomes slide on these threads toward the poles. 2018.2 Question 127 127 What are the changes that occur in the animal cell in telophase of mitosis? Answer The final phase starts when the chromosomes reach the opposite poles of the cell. Then the chromosomes back to their micro-filaments shape. They appear as chromatin network and nucleus division ends. Nucleus division is followed by cytokinesis. In animal cell, cell membranes constricted near cell equator line, through time, this curve and constriction increases gradually until the cell divides into two new cells, each containing a nucleus. 44 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter Question 131 131 1 2017.1 Compare between Prophase and Telophase of mitosis. Answer Prophase Telophase The chromatin network is marked into The chromosomes back to their a number of chromosomes which look micro-filament shape, they appear as thick. chromatin network. The nucleolus and nuclear membrane The nucleolus and nuclear membrane disappear in this phase. appear in this phase. Spindle filaments are formed. Spindle filaments disappear. It is the first phase in mitosis It is the final phase in mitosis. Starts when the chromosomes reach Starts when the interphase ends. the opposite poles of the cell Cytokinesis does not occur in this Cytokinesis occurs. phase. Meiosis 2017.2 Question 132 132 What is the function of meiosis? Answer Maintaining a fixed number of chromosomes for various species during succession of generations where gametes in animals and spores in plants are created. 2004.1 2014.3 Question 133 133 When does meiosis occur? And what is its function (or importance)? Answer Occurs during succession of generations where gametes (eggs and sperms) in animals and spores in plants are created. Function: Maintaining a fixed number of chromosomes for various species. 46 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter 1 2 Zygotene in prophase 1 in meiosis 1. 3 Zygotene in prophase 1 in meiosis 1. 4 Blanks| Synapsis takes place in Zygotene and doubling DNA in interphase. 2008,3 Question 139 139 Synapsis is a distinctive feature in meiosis/why Answer Because it does not occur in mitosis. It occurs in meiosis only, 2002.2 / 2018.1 Question 140 140 What happens to the chromosomes in pachytene? Answer Chromosome condense, thicken and shorten, each chromosome double into two clear chromatids attached to each other via their centromeres. Each two chromatids of the same chromosome are called sister chromatids. At this stage, each pair of homologous chromosomes form a bundle of four chromatids, this bundle is called Tetrad. For example, human cell at this stage has 23 tetrads and 92 chromatids in total. In addition, there is an exchange of genes locations between identical chromosomes, this process is called Crossing Over. Question 141 Fill in the blanks correctly: 1 Tetrad appear in blank 2012.1 2 The centrosome is doubled in and chiasmata are formed in 2017.2 3 Synapsis and chiasmata takes place in 2017.1 / 2018.p Answer 1 pachytene. 2 The centrosome is doubled in interphase and chiasmata are formed in Diplotene. 3 Synapsis takes place in Zygotene and chiasmata in Diplotene 48 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter Question 145 145 1 2021.1 2022.p What is the function of chiasmata? Answer Represent locations for exchanging non-sister chromatids genes. 2024.1 Question 146 146 Where is the location of chiasmata ? Answer points between two non-sister chromatids 2007.2 / 2015.p / 2015.3/ 2017.1 Question 147 147 Explain Diakinesis stage of meiosis. Answer This is the last stage of the prophase at which chromosomes (chromatids of homologous chromosomes) shorten and thicken more. The nucleolus and the nuclear membrane gradually degraded. Locations of chiasmata move to the far end of the chromosomes, thus, chiasmata numbers decrease. 2020.1 2022.2 Question 148 148 Chiasmata numbers decrease in Diakinesis. Answer Because locations of chiasmata move to the far end of the chromosomes. 2021.2 Question 149 149 how distinguishes Metaphase 2 from Metaphase 1 in meiosis? Answer 1 Chromosomes in metaphase 1 are made of four chromatids while chromosomes in metaphase 2 are made of two chromatids. 2 In metaphase 1, chromosomes are attached at the equator as homologous pairs. And in metaphase 2, single chromosomes are attached at the equator. 2. 2010.1 Question 150 150 Write the features of Anaphase Answer 1 Chromatids of each chromosome split when their centromeres separate. 2 Each chromatid represents an independent chromosome moving towards one pole of the cell by spindle filaments. 50 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh  Chapter 1 Question 153 153 2022.1 Compare between Mitosis and Meiosis. Answer Mitosis Meiosis One division Two divisions Two identical cells form by each Four non-identical cells form by each division. division. Genetically identical cells formed. Genetically different cells formed. Number of chromosomes in both new Number of chromosomes in new cells cells is similar to mother cell. is half of those in mother cell. In somatic cells. In reproductive cells. Division occurs during cell life cycle Division occurs after sexual maturity continuously. only. Division is used in sexual reproduction This division is used for growth, repair and having new members of that cells and asexual reproduction. species. 52 ‫األحياء للصف السادس العلمي‬ @mohbio86 @phdmoh