Republic of the Philippines
Department of Education
NATIONAL CAPITAL REGION
SCHOOLS DIVISION OFFICE-MALABON CITY
MALABON NATIONAL HIGH SCHOOL
M. NAVAL ST., HULONG-DUHAT, MALABON CITY
SCIENCE 8: BIOTECHNOLOGY
Name: _____________________________________________
Teacher: __________________________________________
WORKSHEET 1.19
Section: ______________
Date: _________________
KREB’S CYCLE
Learning Competency: Explain the different cell functions.
Instructional Objective: Describe the process of the Krebs cycle
DIRECTIONS: Fill in the molecules created or released during the Krebs Cycle from the loop
of words inside the box. Some words can be used more than once.
Pyruvate
Decarboxylation
Carbon
ATP
FADH2
CO2
NAD+
Oxaloacetate
Hydrogen
Two
Acetyl-CoA
Coenzyme A
Citrate
NADH
Glucose
A. Pyruvate Oxidation
(1) _______________ enters the mitochondrion from the cytoplasm. One (2)_______________ atom
is removed via (3)__________________________ and (4)_____________________ is removed using
(5)____________. (6) ________________ becomes attached to the remaining carbon atoms,
creating (7) _______________, which enters the Krebs cycle.
B. Krebs Cycle
(8) ______________________ enters the cycle then combines with (9) __________________ to make
the six-carbon compounds. During the eight steps of the Krebs cycle, (10) _____________
undergoes a number of reactions, releasing (11) _________ and (12) ______________. (13)
____________ is eventually converted into (14) _______________________ to used again during
Krebs cycle.
C. Products of the Krebs Cycle
(15) __________________is release as waste.
(16) ___________ and (17) ___________ move to the next stage of cellular respiration.
Energy is release in the form of (18) ____________. A glucose molecule produces (19) ________
molecules of ATP because two molecules of (20) _____________ are created from each molecules
of glucose.
Address: M. Naval St., Hulong-Duhat, Malabon City 1470
Telephone Number: (02) 8 361 2174 | 8 373 3263 | 8 372 8808
E-mail Address: malabonnhs.malaboncity@deped.gov.ph
Republic of the Philippines
Department of Education
NATIONAL CAPITAL REGION
SCHOOLS DIVISION OFFICE-MALABON CITY
MALABON NATIONAL HIGH SCHOOL
M. NAVAL ST., HULONG-DUHAT, MALABON CITY
Part II. Sequence the events by assigning numbers (1-5) to show the order in which they
occur during the Krebs cycle.
______ a. Citric acid releases a CO2 molecule and a hydrogen atom to form a five-carbon
compound.
______ b. A four-carbon compound is converted into oxaloacetic acid.
______ c. A five-carbon compound releases a CO2 molecule to form a four-carbon compound.
______ d. A molecule of acetyl CoA combines with oxaloacetic acid to produce citric acid.
______ e. A four-carbon compound releases a hydrogen atom to form another four-carbon
compound.
Part III. The figure below shows the Krebs cycle. Using the information contained in the
passage, write the name of the compound at each lettered block on the lines below the figure.
Use the following labels: “4- carbon compound,” “5-carbon compound,” “Oxaloacetic
acid,” and “Citric acid.” You will use a label more than once.
Reference: Section 7-1: Glycolysis and Fermentation. (n.d.). Retrieved from
http://internet.savannah.chatham.k12.ga.us/schools/ihs/staff/Wells/Shared%20D
ocuments/Biology/Unit%203%20Metabolism/Respiration%20reading%20review.pdf
Address: M. Naval St., Hulong-Duhat, Malabon City 1470
Telephone Number: (02) 8 361 2174 | 8 373 3263 | 8 372 8808
E-mail Address: malabonnhs.malaboncity@deped.gov.ph